you can review all the RM catalogues i've scanned and archived over the years with the google drive link below to confirm what size seatpost you need:
https://drive.google.com/drive/folders/0B1XobjfaP4GpNnFqclNoUDdCWUE?resourcekey=0-r1rq7bj0D3D8q9Wtnc5vLw&usp=drive_link