Add a text in every page

PdfDocument pdfdoc = new PdfDocument();
           PdfPageBase page = pdfdoc.Pages.Add();

           PdfSignatureField signaturefield = new PdfSignatureField(page, "Signature");
           signaturefield.BorderWidth = 1.0f;
           signaturefield.BorderStyle = PdfBorderStyle.Solid;
           signaturefield.BorderColor = new PdfRGBColor(System.Drawing.Color.Black);
           signaturefield.HighlightMode = PdfHighlightMode.Outline;
           signaturefield.Bounds = new RectangleF(100, 100, 100, 100);
           pdfdoc.Form.Fields.Add(signaturefield);
           pdfdoc.SaveToFile("AddSignField.pdf", FileFormat.PDF);