This sample shows how to add free text annotations to your PDF document.
Use PDFFreeTextAnnotation class to add text annotation.
PDFDocument pdf = new PDFDocument(); pdf.Pages.Add(new PDFPage(PDFPaperFormat.A4)); PDFFreeTextAnnotation annot = new PDFFreeTextAnnotation(100, 100, 150, 100); annot.Contents = "Free text annotation"; pdf.Pages[0].Annotations.Add(annot); pdf.Save("TestFreeTextAnnotation.pdf", true);