The Mac Preview app allows you to easily and quickly fill out the PDF forms. As for how to fill out the PDF form Preview, here are easy and quick tips for you!

Step 1. Launch Preview on your Mac. Open your PDF form with Preview. Control-click on the document and select "Open with Preview". You can also go to the "Preview" main menu and click "File" > "Open".

Step 2. You can directly fill out interactive forms in Preview. If your form is non-interactive, you can click on "Tool > Annotate > Text" and then the font icon to choose font size and style.

Step 3. Click on the field to start typing text. You can change the color of the text and more. Once you've finished making edits, save your work.

Source : https://pdf.wondershare.com/pdf-editor-mac/fill-out-pdf-forms-in-preview.html