Dear please check the code.
Why you need to export in multiple files, it is bad as suppose you have a report with 300 pages result, then are you think to make 300 files to export and customer to check each & every files. Think again.
Still here is solution, Please refer to the following VB.Net code for exporting to seperate pdf files.
Dim rdoc As New ReportDocument
'------------------------------------
'Add your code to set rdoc object
'--------------------------------------
Dim exportOpts As ExportOptions = New ExportOptions()
Dim pdfRtfWordOpts As PdfRtfWordFormatOptions = ExportOptions.CreatePdfRtfWordFormatOptions()
Dim destinationOpts As DiskFileDestinationOptions = ExportOptions.CreateDiskFileDestinationOptions()
For li_count As Integer = 1 To pagecount
pdfRtfWordOpts.FirstPageNumber = li_count
pdfRtfWordOpts.LastPageNumber = li_count
pdfRtfWordOpts.UsePageRange = True
exportOpts.ExportFormatOptions = pdfRtfWordOpts
exportOpts.ExportFormatType = ExportFormatType.PortableDocFormat
destinationOpts.DiskFileName = "D:\report File" & li_count & ".pdf"
exportOpts.ExportDestinationOptions = destinationOpts
exportOpts.ExportDestinationType = ExportDestinationType.DiskFile
rdoc.Export(exportOpts)
Next
refer link export in multiple file
You have not written your CR-version, So please refer to this link also which says, not able to export in multiple files in cr-2008.
http://social.msdn.microsoft.com/Forums/en-US/f85e167d-edb3-44d0-82fc-2d2b6f92f57b/how-do-i-export-multiple-pdf-files-from-a-single-crystal-report-ie-a-pdf-file-for-each?forum=vscrystalreports
http://scn.sap.com/thread/1132776