I think you need crystal report XI (ie 11), this is the first version to support .rpt.
If you look into following directory on your web server:
*aspnet_client\system_web\2_0_50727\CrystalReportWebFormViewer4\JS*
or full path for most web servers
*C:\Inetpub\wwwroot\aspnet_client\system_web\2_0_50727\CrystalReportWebFormViewer4\js*
Open up the export.js file look for the following code if you see it then it should be able to export to rtf and/or you need to make sure you have the Crxf_rtf.dll which enabled exporting to rtf. See this doc for more detail Exporting Changes in Crystal Reports from 8.5 to XI.
if( rpt )
{
list += "<OPTION value=\"CrystalReports\">" + L_CrystalRptFormat + "</OPTION>";
}
if( pdf )
{
list += "<OPTION value=\"PDF\">" + L_AcrobatFormat + "</OPTION>";
}
if( word )
{
list += "<OPTION value=\"MSWord\">" + L_WordFormat + "</OPTION>";
}
if( xls )
{
list += "<OPTION value=\"MSExcel\">" + L_ExcelFormat + "</OPTION>";
}
if( recXls )
{
list += "<OPTION value=\"RecordToMSExcel\">" + L_ExcelRecordFormat + "</OPTION>";
}
if( rtf )
{
list += "<OPTION value=\"RTF\">" + L_RTFFormat +"</OPTION>";
}