This sample shows how to add text markup annotations (highlight, strikeout, underline) to your PDF document in C# and VB.NET.
Use the PdfPage.AddHighlightAnnotation method to highlight and annotate a page area.
To strike out or underline a page area, use PdfPage.AddStrikeoutAnnotation, PdfPage.AddJaggedUnderlineAnnotation and PdfPage.AddUnderlineAnnotation methods.
All these methods create an annotation and return an instance of a PdfTextMarkupAnnotation subclass. You can call the SetTextBounds method to change the annotated area. It is possible to change the Contents and the Color properties, too.