This post helps to add a text box to PDF using a free software and an online tool. You can adjust the size of text box, text style, etc.

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.

You can type on a PDF using one of several different options, depending on the device you are using.

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.

Widely used PDF files capture text and images nearly exactly as they display in the application that created them. The format is designed to store text and both bitmapped and vector images, with the ...

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.