Add image to multiple page pdf

I have a 9 page pdf document. I am trying to add a watermark to pages 1,3,5,7,8,9. See my code below, I'm having issues adding the image to the page sequence.

Using inputPdfStream As Stream = New FileStream(Server.MapPath("~") + "/Application.pdf", FileMode.Open, FileAccess.Read, FileShare.Read)
      Using inputImageStream As Stream = New FileStream(Server.MapPath("~") + "/Signature.png", FileMode.Open, FileAccess.Read, FileShare.Read)
            Using outputPdfStream As Stream = New FileStream(Server.MapPath("~") + "/Application2.pdf", FileMode.Create, FileAccess.Write, FileShare.None)
                  Dim reader = New PdfReader(inputPdfStream)
                  Dim stamper = New PdfStamper(reader, outputPdfStream)
                  Dim pdfContentByte = stamper.GetOverContent(1)

                  Dim image As iTextSharp.text.Image = iTextSharp.text.Image.GetInstance(inputImageStream)
                  Dim pages As Integer = reader.NumberOfPages
                  For i As Integer = 1 To pages

                        image.SetAbsolutePosition(100, 100)
                        pdfContentByte.AddImage(image)

                  Next
                  stamper.Close()
            End Using
      End Using
End Using