[PDFNet] How can I select perticular text in PDF document and add custom annotation to it?

Yes, you can use PDFViewCtrl.selectByRect() with four points that describe a tiny rectangle and then you can use PDFViewCtrl.getSelection() to retrieve the information for highlighting. Please find more information about this from https://groups.google.com/forum/?fromgroups#!searchin/pdfnet-sdk/getSelection/pdfnet-sdk/79uApMPEu_M/CSCn62vsm8QJ