Most electronic documents are saved in PDF format these days, especially the files with lengthy documents. While PDF is a great tool, there are instances when you have to deal with the issues of not being able to highlight important information in PDF eBooks and other materials when reading for future reference. Many readers, including Adobe, will only allow users to highlight files if they have rights to the document.
If you are having problem with highlighting a PDF on Mac, you could opt for a program called iSkysoft PDF Editor for Mac. This is an all-one tool for Mac and it has the capabilities to convert, annotate, edit or highlight PDF text easily.
Normally we use the Highlight Text button ("T") to highlight text with yellow,green,red or other colors. In addition to highlighting text, this professional PDF Editor provides more tools for users to annotate/mark up the content on a PDF document.
Highlight Texts in Yellow/Green/Pink or other Colors (Highlight PDF Mac)
You can easily highlight PDF texts on Mac with a selected color. Just click the "Highlight" (T) button and select any text you want in your PDF document. The selected texts will be highlighted with the default light-yellow color. To change to other colors like Green, go to Tools > Inspector. In the dialog that opens, switch to Annotation Properties and click Fill Color open to pick a color you want. Then highlight PDF texts with the color you've chosen. Now you can use this tool to highlight important sentense and key points in a PDF. Besides highlighting, you can also underline or strike through any selected text. All these functions help you mark the content easily. To do so, just click the T button again for a drop-down menu to select the tool you want.
Add Sticky Note and Text Box
Sticky Note and Text Box let you add annotations to any position you want. They can hold lots of texts and sentences. To add a Sticky Note or a Text box, first choose Sticky Note or Text Box (click twice to open the menu) from the tool bar, and then click on any position in the PDF document. To input texts, double click Sticky Note or Text Box icon to enter editing mode. The Sticky Note and Text Box have default colors, but you can change the colors in Inspector (Go to Annotation Properties tab for border colors and go to Text Properties tab for font colors).
Draw Line Annotations
Click the Arror icon twice on top to open the menu as shown below and choose the tool you want to draw shapes on your PDF document.
Add Free-hand Drawing and Links
Similarly, click the Pencil button twice to open a menu to choose from Pencil, Eraser and Link tools. Then you're able to add free-hand drawings in your PDF document, remove drawings by the Eraser tool, and add a link to an internal PDF page or an external web page.
Below is a snapshot of the exported PDF file I've annotated on iSkysoft PDF Editor for Mac.
Also see the video tutorial about how to highlight PDF document:
Part 2. How to Highlight PDF on Windows/PC
Highlighting PDF files is actually one of the most widely used methods for markup while reading as it helps to find vital information and organize notes. You could capture specific words throughout a document or just highlight an entire phrase or one sentence. After using the iSkysoft PDF Editor for Windows (PDF Highlighter for Windows), the highlighted documents can be saved in any location and send to others with all the emphasized areas preserved. When you highlight text in your PDF files, especially with long articles, this will make it easier for you to identify the key points easily to save lots of reviewing and studying time.
iSkysoft PDF Editor is recommended because it is a multi-functional tool that is compatible with all Adobe PDF files. Choosing this tool for PDF highlight will allow you to edit files just as easy as with a Word Processor. Aside from using the annotation tools for highlighting, you will have other options to insert images and text; underline and strike out text; edit, convert and create PDFs in a single program.