Hi rhino000,
Refer the below code to add line in pdf.
// Paragraph to draw line.
Paragraph p = new Paragraph(new Chunk(new iTextSharp.text.pdf.draw.LineSeparator(0.0F, 100.0F, Color.BLACK, Element.ALIGN_LEFT, 1)));
// call the below to add the line when required.
ds.Add(p);
Or you can use line separator also.
LineSeparator line = new LineSeparator(1f, 100f, Color.BLACK, Element.ALIGN_LEFT, 1);
ds.Add(line);