XtraReports program has the capability to export its own reports (*.prnx) to many different formats, including the RTF. So just simply use the export function in the program.
Convert XtraReports report to Rich Text Format document.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert prnx to rtf on Windows
Reporting Tool for WinForms, ASP.NET, Silverlight, WPF and LightSwitch
Convert from prnx file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.