Fill out and sign PDF forms in Preview on Mac
Some PDFs are forms you can fill out and then print or send. If a form requires a signature, you can add your signature to any PDF.
Fill out a PDF form
In the Preview app
on your Mac, open the PDF form.Click a field or a line in the form.
A text annotation box automatically appears.
Type your text in the field.
If you save the form (by choosing File > Export), you can close it, reopen it later and continue to fill it out.
Create and use signatures
You can capture your signature using your trackpad or a camera on your Mac to reuse in PDFs.
In the Preview app
on your Mac, if the Markup toolbar isn’t showing, click the Show Markup Toolbar button 
, then click the Sign button 
.Follow the on-screen instructions to create and save your signature.
Create a signature using your trackpad: Click Trackpad, click the text as prompted, sign your name on the trackpad using your finger, press any key, then click Done. If you don’t like the results, click Clear, then try again.
If your Mac has a Force Touch trackpad, you can press your finger more firmly on the trackpad to sign with a heavier, darker line.
Create a signature using your computer’s built-in camera: Click Camera. Hold your signature (on white paper) facing the camera so that your signature is level with the blue line in the window. When your signature appears in the window, click Done. If you don’t like the results, click Clear, then try again.
Add the signature to your PDF.
Choose the signature you want to use, drag it to where you want it, then use the handles to adjust the size.
If you use iCloud Drive, your signatures are available on your other Mac computers that have iCloud Drive turned on.
Delete a saved signature
In the Preview app
on your Mac, if the Markup toolbar isn’t showing, click the Show Markup Toolbar button .Click the Sign button
, then click the X to the right of the signature you want to delete.