Edit: Sorry I wasn't familiar with rdlc report viewer. This should help you
http://msdn.microsoft.com/en-us/library/ms252091.aspx[
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This is how I have done it in the past. Not sure if you are using print document or not.
(I just quickly converted from VB.NET so hopefully I got the syntax all correct)
The key is the StandardPrintController.
PrintDocument1 = new PrintDocument();
PrintDocument1.DocumentName = "MyPrint";
PrintDocument1.PrinterSettings = ps;
StandardPrintController silentController = new StandardPrintController();
PrintDocument1.PrintController = silentController;
PrintDocument1.DefaultPageSettings.Margins.Top = 20;
PrintDocument1.DefaultPageSettings.Margins.Left = 20;
PrintDocument1.DefaultPageSettings.Margins.Right = 20;
PrintDocument1.DefaultPageSettings.Margins.Bottom = 20;
PrintDocument1.Print();