How to Highlight a PDF Document With Adobe Reader 9

Check Permission to Comment
1. Open a PDF file in Adobe Reader 9.
2. Select 'Document' in the top menu bar and choose 'Security' and 'Show Security Properties' from the drop-down menu.
3. Read the 'Document Restrictions Summary.' It will say 'Commenting: Allowed' if the document settings allow you to highlight and comment on the PDF file. If it says 'Commenting: Not Allowed,' you cannot highlight and add comments to the PDF file. If it says 'Content Copying: Allowed' you will be able to highlight a selection of text to copy and paste to another file.
Highlight a PDF
4. Click on 'Tools' in the top menu bar. Select 'Comment & Markups' and the 'Highlight Text' tool. The highlight text tool is a square button that has the letter 'T' inside that has been highlighted in yellow. It also has a yellow highlighter in the top left of the button.
5. Click and drag the mouse pointer over the section of text you wish to highlight. To highlight larger areas, press 'Ctrl' on the keyboard, click with a mouse and drag to highlight an entire rectangular area of text.
6. Save the PDF document so you can view your highlighting the next time you open the document.