I'm posting this mostly for my own benefit since every time I need it I spend 20 minutes googling around to get the code snippet again.

So here's the article: LINK

Here's the Code:

TelerikReportingExportToPdf.csView on GitHub
void ExportToPDF(Telerik.Reporting.Report reportToExport)
    {
        ReportProcessor reportProcessor = new ReportProcessor();
        RenderingResult result = reportProcessor.RenderReport("PDF", reportToExport, null);
  
        string fileName = result.DocumentName + ".pdf";
  
        Response.Clear();
        Response.ContentType = result.MimeType;
        Response.Cache.SetCacheability(HttpCacheability.Private);
        Response.Expires = -1;
        Response.Buffer = true;
  
        Response.AddHeader("Content-Disposition",
                           string.Format("{0};FileName=\"{1}\"",
                                         "attachment",
                                         fileName));
  
        Response.BinaryWrite(result.DocumentBytes);
        Response.End();
    }

So you can change the extensions to the following:

  • IMAGE
  • PDF
  • RTF
  • MHTML
  • XLS
  • CSV
  • XPS

This comes from here: LINK