PDF Digital Signing Disable CRL - c#-4.0

Question

I am writing a sample pdf signer using itextsharp.dll n the digital signature is on a usb device.
it's working nicely only problem is that some times the signing gets completely stops for hours together.
I have found that the signing process goes to digital issuer site to get CRL to embed in the signed document increasing it's size from 100kb to 1300kb+ and also signs document very slow due to getting CRL from issuer site.
but if I disable internet the file gets signed very fast and size increase is just 5-10kb.
So my question precisely is how can I instruct the signing process not to go online to get CRL n simply sign the document fast with less size increase in original document.
public void Sign(ICollection<X509Certificate> chain, X509Certificate2 pk,
String digestAlgorithm, CryptoStandard subfilter,
String reason, String location,
int estimatedSize)
{
IList<ICrlClient> crlList = new List<ICrlClient>();
crlList.Add(new CrlClientOnline(chain));
// Creating the reader and the stamper
PdfReader reader = null;
PdfStamper stamper = null;
FileStream os = null;
//int noofpdfs = 0;
var watch = Stopwatch.StartNew();
try
{
string[] srcfiles;
if (lblSplitedFilePath.Text.Equals("Split By Page Directory"))
srcfiles = Directory.GetFiles(tbsrcpath.Text, "*.pdf");
else
if (tbsrcpath.Text.ToUpper().Contains(#"\SPLIT"))
srcfiles = Directory.GetFiles(tbsrcpath.Text, "*.pdf");
else
srcfiles = Directory.GetFiles(tbsrcpath.Text + #"\split\", "*.pdf");
//int noofpdfs = srcfilePaths.Count();
for (int i = 0; i < srcfiles.Count(); i++)
{
// Get FileName
lblOutputFile.Text = tbtgtpath.Text + #"\" + Path.GetFileName(srcfiles[i]);
lblOutputFile.Refresh();
os = new FileStream(lblOutputFile.Text, FileMode.Create);
reader = new PdfReader(srcfiles[i]);
iTextSharp.text.Rectangle pdfbox = reader.GetPageSize(1);
stamper = PdfStamper.CreateSignature(reader, os, '\0');
// Creating the appearance
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
if (!string.IsNullOrWhiteSpace(tbContact.Text))
{
appearance.ReasonCaption = "Contact:";
appearance.Reason = tbContact.Text;// reason;
}
appearance.Location = location;
//Adding Image to Sign
if (cbAddImageSign.Checked)
{
var image = iTextSharp.text.Image.GetInstance(tbSignImage.Text);
appearance.Acro6Layers = true;
appearance.SignatureGraphic = image;
appearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.GRAPHIC_AND_DESCRIPTION;
}
int llx, lly, urx, ury;
int.TryParse(Tbllx.Text, out llx);
int.TryParse(tblly.Text, out lly);
int.TryParse(tburx.Text, out urx);
int.TryParse(tbury.Text, out ury);
pdfSigning.Properties.Settings.Default.llx = llx;
pdfSigning.Properties.Settings.Default.lly = lly;
pdfSigning.Properties.Settings.Default.urx = urx;
pdfSigning.Properties.Settings.Default.ury = ury;
appearance.SetVisibleSignature(new iTextSharp.text.Rectangle(llx, lly, urx, ury), 1, "sig");
//Add Water mark
if (!lblWaterMarkImagePath.Text.Equals("Pdf Water Mark Image Path"))
{
var wmimage = iTextSharp.text.Image.GetInstance(lblWaterMarkImagePath.Text);
wmimage.SetAbsolutePosition(0, 0);
wmimage.ScaleToFit(100, 100);
for (var j = 0; j < reader.NumberOfPages; j++)
{
var content = stamper.GetUnderContent(j + 1);
content.AddImage(wmimage);
}
}
//appearance.setRenderingMode(PdfSignatureAppearance.RenderingMode.GRAPHIC);
// Creating the signature
try
{
IExternalSignature pks = new X509Certificate2Signature(pk, digestAlgorithm);
MakeSignature.SignDetached(appearance, pks, chain, crlList, null, null, estimatedSize,
subfilter);
}
catch (CryptographicException ex)
{
MessageBox.Show(ex.ToString());
}
//noofpdfs++;
if (cbPrintOnSign.Checked)
{
switch (tbPrintMethod.Text)
{
case "2":
SendFileToPrinter(lblOutputFile.Text, printpdf2printer);
break;
default:
SendToPrinter(lblOutputFile.Text);
break;
}
}
if (cbDeletePdfPostSign.Checked)
{
File.Delete(srcfiles[i]);
}
dgvPrintFiles.Rows.Add(srcfiles[i].ToString());
}
lblOutputFile.Text += #" Siging Over:Signed " + srcfiles.Count().ToString() + " Files";
}
finally
{
if (reader != null)
reader.Close();
if (stamper != null)
stamper.Close();
if (os != null)
os.Close();
}
watch.Stop();
var elapsedMs = watch.ElapsedMilliseconds;
MessageBox.Show("Signing Time:" + elapsedMs / 1000 + " Second");
}