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.

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.

Try Foxit Reader 4.3, which allows you to add text to any PDF. After installing the program, simply open your PDF in Foxit instead of Adobe Reader, then click Comments, Typewriter Tools, Typewriter ...