var report = new ReportViewer();
report.ProcessingMode = ProcessingMode.Local;
report.LocalReport.ReportPath = Server.MapPath("~/Reports/MyReport.rdlc");
report.LocalReport.DataSources.Add(new ReportDataSource("MyDataSource", myData));
byte[] bytes = report.LocalReport.Render("PDF", null, out mimeType, out encoding, out extension, out streamIds, out warnings);