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How can I type into a PDF file.
Of course, if it was from a Mac, you could use Preview to "Annotate" with text and/or a rectangle and/or an ellipse.
[attachment=1040:Annotati..._Preview.jpg]
Otherwise, you could still use Preview to draw the rectangle and/or an ellipse and print (as a file to send back) that page, as a PDF. Any notes, corrections, suggestions would have to be in another PDF.
I can't verify that these 'notations' will appear in Acrobat, however. I don't even have that installed, anymore!