Learn how to display text set apart from your main document in Google Docs with either a table or an inserted drawing.

Did you know you can add a text box filled with color or a unique shape to your Google Doc? Here's where you'll find that feature in Google Drive.

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.