Choose the signature type before you edit anything
A visible electronic signature is the signature-looking object many people expect: a typed name, a drawing, or an image placed by the signer. In Apple Preview and iPhone Markup, the Signature control creates and places that kind of visible mark. Adobe Fill & Sign can type, draw, or insert an image of handwriting. Adobe says saving makes that signature and related text part of the PDF; see Adobe’s Reader instructions.
A certificate-based digital signature is a different PDF feature. It uses a digital ID with a private key for signing and a certificate for verification. The visual rectangle may be visible, but it is the certificate operation that provides the technical signature. A scanned autograph or typed name does not become a certificate-based signature simply because it is saved in a PDF.
Read the request first. Instructions to add a signature, initials, or name commonly point to a visible-signature workflow. A request for a digital ID, certificate, cryptographic signature, or viewer validation points to a certificate-based workflow. If that is unclear, ask which method and signing sequence are expected before proceeding. Also check that the file is the intended version and that the signature line names your role.
| If you need… | Start with… |
|---|---|
| A clear signature mark placed on a page | A visible electronic signature in Preview, Markup, or Acrobat Fill & Sign. |
| A signature that PDF software can validate with certificate information | Acrobat’s certificate-based digital-signature workflow and an appropriate digital ID. |
| Several people to complete a document | The stated signing order and each person’s permission; do not assume the first signature leaves the file editable. |
| A corrected file after someone signed it | An unsigned original or a newly issued copy, not a workaround that alters a signed revision. |
Do four checks before you sign the PDF
Work from the original attachment, download, or shared file, then save a working copy before making changes. An unsigned backup is especially important before a certificate signature because a signed PDF can become difficult to correct. Adobe’s permissions guidance recommends preserving an unsigned copy.
Review every page at normal zoom. Confirm the version, page count, fields, dates, and signature location. A PDF may have interactive fields or may be a flat page that only looks like a form. Use a designated signature field when one is provided. Do not cover instructions, another person’s field, or content that will be needed on printouts.
Check permission messages before editing. A viewer may say that filling, editing, or signing is restricted, or show certificate status. Do not remove restrictions or print-and-rescan to work around them. Request an editable or correctly configured copy. For several signers, agree the order first: Adobe says certification must be applied before other signatures, and Lock document after signing can prevent later edits and signatures.
Keep the original: Do not overwrite the only unmodified PDF. Preserve it before you type, draw, sign, or lock anything.
Confirm your role: Check whether the line is for a signer, approver, witness, preparer, or another named role. Fill only the fields assigned to you.
Read messages from the PDF: Warnings about permissions, certificates, or locked fields are instructions to investigate, not prompts to bypass.
Plan the sequence: Where more than one signature is expected, identify who signs first and whether later changes or signatures must remain possible.
How to sign a PDF on Mac with Preview
Preview is useful for placing a visible electronic signature on a Mac when the PDF is editable in that workflow and a certificate signature is not required. Apple’s Preview guide says it can capture a signature with a trackpad, the Mac’s built-in camera, or a nearby iPhone or iPad. This places a visual mark; it is not a substitute for a digital ID.
Complete relevant fields before placing the signature and save a copy under a new name. Apple notes that not every PDF permits direct typing, so a text box may be needed. Preview can retain signatures, and Apple says iCloud Drive can make them available on other Macs. Delete obsolete saved signatures. The nearby-device option has Continuity requirements, and toolbar labels can vary by macOS version.
Open a copy in Preview
Open the intended PDF, inspect its pages and fields, and save a separate working copy before signing.
Show Markup
Select the Show Markup Toolbar button if the toolbar is not already visible, then select the Sign button.
Create or choose a signature
Choose an existing signature, or create one with Trackpad, Camera, or a nearby iPhone or iPad. With a trackpad, sign with a finger and press a key; with a camera, hold a signature on white paper level with the displayed guide; on a nearby device, sign and tap Done.
Place and size it
Select the signature, drag it to the intended line, and use the handles to adjust its size. Keep it readable without covering labels or nearby fields.
Review and save
Check the page at normal viewing size, verify the filename and page count, then save the signed copy. Reopen it once to confirm the placement is preserved.
How to sign a PDF on iPhone with Markup
On iPhone, Markup can add a visible electronic signature in a supported app. Apple’s Markup instructions direct you to Markup, Add, then Add Signature. Select or create a signature with your finger, drag it into place, and resize it with blue dots. Rotate the phone for more room when drawing if useful.
Apple’s current Preview on iPhone guide also describes opening a PDF, using Form Filling, and using Add for a signature or text form box. The route depends on the app and iOS version. Review the result at close and normal zoom, save a clearly named copy, and reopen that copy before sharing it.
Open the correct PDF
Start from the intended file and make a duplicate if the app provides a way to save a separate copy.
Enter Markup
In a supported app, tap the Markup button or Markup. For a fillable PDF in the current iPhone Preview app, Apple directs you to Form Filling first.
Add the signature
In the Markup toolbar, tap Add and then Add Signature. Choose an existing signature or use Add or Remove Signature to create another one.
Draw, label, and place
Sign with a finger, tap Clear if you need another attempt, optionally label the signature, and tap Done. Drag the placed signature to the intended location and use the blue dots to resize it.
Save a finished copy
Review at close and normal zoom, then save or export the PDF as a clearly named completed copy. Reopen that copy before you send it onward.
How to add a visible signature in Adobe Acrobat or Reader
Adobe’s visible-signature route is Fill & Sign. Its current Reader guide says to open the PDF, choose the Sign icon or Tools > Fill & Sign, choose Fill and Sign, and use Sign to add a signature or initials. The first-time panel offers Type, Draw, and Image. Those are visible electronic-signature choices, not certificate-based digital signatures.
Fill assigned fields first, but do not treat automatic field detection as proof that every field is correct. After Apply, click the intended location and use the controls or arrow keys to refine placement. Adobe says signature and text become part of the PDF when saved. Product availability, subscriptions, and labels can differ by product and version; its help notes that current and classic experiences may not match. Use the current official help if your interface differs.
Open Fill & Sign
Open the PDF in Acrobat or Reader. Select the Sign icon, or open Tools > Fill & Sign when that route is shown in your interface, then choose Fill and Sign.
Complete assigned fields
Review detected fields and enter only the requested information. Recheck the document before placing the signature.
Choose Add Signature or initials
Select the Sign icon and choose signature or initials. Select an existing saved item or make a new one by typing, drawing, or importing a clean image.
Apply and position
Select Apply, click the location on the PDF, and then adjust the field using its controls or arrow keys until it sits correctly.
Save and verify
Save a completed copy, reopen it, and confirm the signature, text, page order, and filename. Keep the unsigned original separate.
How certificate-based digital signatures work in Acrobat
Use this route only when a certificate-based signature is specifically expected and you have an appropriate digital ID. Adobe says a digital ID contains a private key for signing and a certificate for verification. IDs can be self-created or issued by a third party, but a self-created ID may not meet the recipient’s trust or process requirements. Confirm the accepted certificate source, identity details, and validation expectation before creating or choosing an ID.
Adobe’s current instructions direct users to All tools > Use a certificate, then Digitally sign. You draw a signature rectangle, choose a Digital ID, verify details, enter its password, select Sign, and choose where to save. Configure New Digital ID is part of this certificate workflow, not ordinary Fill & Sign.
The optional Lock document after signing setting is consequential. Adobe says it can prevent further edits, and its permissions guidance says it blocks added signatures. Do not use it where later signers are expected unless the agreed process calls for it. Certification must occur before other signatures in Adobe’s model, so settle the preparation and sequence before the first certificate signature.
Confirm the certificate requirement
Verify that a certificate-based digital signature is required and identify the accepted digital ID or certificate source before opening the signing tool.
Preserve a clean original
Save an unsigned backup. Check the document’s permissions and whether any other signature or certification must happen first.
Open the certificate tool
In Acrobat, select All tools > Use a certificate, then select Digitally sign. Read the instruction dialog and continue only if the file and signing order are correct.
Define the appearance and identity
Draw the signature rectangle, choose the intended Digital ID, verify the displayed details, and enter the Digital ID password when prompted.
Decide deliberately about locking
Select Lock document after signing only when no permitted later edits or signatures are required. Then select Sign and save the new signed PDF.
Validate the result in a PDF viewer
Open the saved PDF and inspect the signature status and any warnings. If a certificate is untrusted or the result differs from the required process, stop and ask for direction rather than altering the signed copy.
Signing order, permissions, and what to do when a PDF is locked
For a PDF with more than one signature, agree a simple sequence before anyone signs: who prepares it, who signs next, whether fields must remain editable, and who retains the unsigned original. A signature line’s position is not proof of order. Form settings, certification rules, and recipient instructions can impose a different sequence.
Adobe explains that a digital-ID signature can lock a PDF, and Lock document after signing blocks edits and added signatures. If you are the only signer, Acrobat may permit clearing your signature to make changes. When others have signed, Adobe directs users to request an unsigned original or ask the relevant signer to remove a signature. Do not edit around a signed revision.
Visible signatures can also cause practical errors: they may cover a field, be on the wrong version, or be placed before a required change. Return to the clean original, correct the content, and create a new completed copy. Use distinct filenames for draft, unsigned final, and signed final.
If the first signature locks the PDF: Stop the sequence and request a new unsigned or properly configured copy from the document owner. Do not convert, print, or rescan it to evade the restriction.
If a signature field will not accept your entry: Check whether the field is assigned, locked, or outside your role. Ask for the intended signing method rather than drawing over the field.
If you need to correct content: Use the clean original or an authorized replacement. A corrected content revision should be signed again through the expected process.
If certificate status shows a warning: Treat it as an issue to resolve with the certificate owner or recipient. Do not assume a visible appearance alone fixes certificate trust or validation.
Finish the document workflow without confusing tools
After review, keep the signed PDF and its unsigned original together under a clear naming convention. If a later job is to capture invoice or receipt details, use the separate PDF Extractor workflow. For statements, the bank statement extractor is a separate route for extracting bank transactions; neither tool signs or alters the PDF.
For routine administration, create a new invoice with the invoice creator and track business spending in the expense manager. Those links are follow-through for different work, not ways to sign, edit, or alter a PDF. Review Pedfs options on pricing if that next workflow is relevant.
The reliable finishing habit is simple: preserve the original, save and reopen the signed copy, confirm it matches the requested signature type and order, then move to the next specific task.
Explore the Pedfs homepage to see the financial-document tools together, or compare the available features and allowances on the pricing page.