The PDF files we've come to know and love have selectable text. But did you know? Not all PDFs are created equal. Some PDF files have text that can't be selected!
Some processes (like extracting a page from a PDF in Adobe Acrobat) will render the PDF as an image and remove the ability to select text.
How can you tell?
If you've uploaded a PDF into Critique^It, and text cannot be highlighted with the text tool, its an image.
No worries, you can still use the square, arrow, circle and freehand tools to highlight and leave feedback.