This article show three methods that can be used to add audio comments to PDF documents in Adobe Acrobat free and Pro version.

Need to edit a PDF document but don’t want to pay for the more expensive Adobe editors? You can add text to and sign a PDF with just the free Reader program.

In other words, Adobe Reader won't let you add text. What you need is a program that's a little more accommodating, PDF-wise. Try Foxit Reader 4.3, which allows you to add text to any PDF.

If you’re using a Mac, the process of creating a digital signature on a PDF document is easy. You can create a digital signature by using the built-in Preview app.

It's not immediately obvious, but when viewing PDF documents in the Files app, there are hidden tools that enable you to rotate pages, add blank pages, insert images, delete pages, and even scan ...

If you need to sign a PDF document from your Android phone, there are a variety of apps available, but the most well-known is the free version of Adobe Acrobat Reader.