sap.Acro6Layers = true;
            sap.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.DESCRIPTION;
            sap.SetVisibleSignature(new iTextSharp.text.Rectangle(30, 830, 170, 770), 1, "Signature"); //reader.NumberOfPages
            // vvvvv
            PdfTemplate layer2 = sap.GetLayer(2);
            String text = "Это блок подписи\n "
                    + "Линия 2\n"
                    + "Линия 3\n";
            Font font = new Font();
            float size = font.Size;
             float MARGIN = 2;
            Rectangle dataRect = new Rectangle(
                    MARGIN,
                    MARGIN,
                    sap.Rect.Width- MARGIN,
                    sap.Rect.Height - MARGIN);
            if (size <= 0)
            {
                Rectangle sr = new Rectangle(dataRect.Width, dataRect.Height);
                size = ColumnText.FitText(font, text, sr, 12, sap.RunDirection);
            }
            ColumnText ct = new ColumnText(layer2);
            ct.RunDirection=(sap.RunDirection);
            ct.SetSimpleColumn(new Phrase(text, font), dataRect.Left, dataRect.Bottom, dataRect.Right, dataRect.Top, size, Element.ALIGN_LEFT);
            ct.Go();