Adding Text Notes to a PDF Select the Text Box tool from the Drawing Markups panel. Click, or click and drag, on your document to add a box with a colored border, and type your observations in it.

Sometimes when you need to save a presentation in PDF format, some hyperlinks and notes can be lost. To avoid this problem, you can use the OpenOffice software to save Powerpoint presentation or PPT ...

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.