How to sign a PDF on a Mac and add your signature

With PDF Unlimited (free)

1. Open the document

   Open the PDF in PDF Unlimited and scroll to the signature line. ⌘+ zooms in if the line is tiny.

2. Switch to Sign mode

   Click Sign in the toolbar mode switcher.

3. Create your signature

   Draw it with one finger on the trackpad, or type your name. It is saved, so you only do this once.

4. Place and resize

   Click where the signature should go. Drag it to fine-tune the position and drag a corner to resize it so it sits on the line.

5. Fill the rest

   If there are fields for your name or date, click into them and type. If there are no fields, add a text box in Annotate mode.

6. Save and send

   Save the PDF. If it is too large for email, use File > Export Compressed… first.

With Preview, built into macOS

1. Open the Markup toolbar

   Open the PDF in Preview and click the Show Markup Toolbar button. Then click the Sign button.

2. Create a signature

   Choose Trackpad and sign with your finger, then press any key and click Done. You can also choose Camera and hold up a signature written on white paper, or pick a nearby iPhone or iPad and sign on its screen.

3. Place it

   Click the signature in the list to add it, drag it into place, and use the handles to resize it.

Tips for a PDF signature that looks right

Signing on a trackpad feels odd the first time. Go slower than you would on paper and sign larger than you need; it scales down cleanly. If it looks shaky, clear it and try again. Nobody will see the drafts.

Typed signatures are fine for most everyday documents like rental forms, school permission slips and freelance contracts. If a document asks for a handwritten-style signature, draw it.

Is a PDF signature legally valid?

In many places, including the US under the ESIGN Act, an electronic signature is generally valid for ordinary contracts when everyone agrees to sign electronically. A drawn or typed signature placed on a PDF counts as an electronic signature.

Some documents need more, like notarized forms or agreements that require a certificate-based digital signature. If the other side specifically asks for a "digital signature" with a certificate, a drawn signature will not satisfy that. When in doubt, ask whoever sent you the document. This is general information, not legal advice.

When the form has fields

Many PDFs come with fillable fields. In PDF Unlimited you just click into a field and type, no mode switch needed. If clicking does nothing, the PDF is a flat scan or an export without fields. Use a text box instead. Our guide to filling out PDF forms covers both cases.

Keep the signed copy safe

A signed contract is worth protecting. Before you email it, consider adding an open password with File > Password Protect… and sending the password by text message, not in the same email. See how to password protect a PDF.

Everything happens on your Mac. Your signature is never uploaded anywhere, which is more than most free online signing sites can say.

Questions