Dear Tina :
Note that you can select Input | Ground Geometry | Adjust Geometry. The Adjust Geometry dialog box will allow you to set the cross-section station numbering to match whatever criteria you specify.
Note that you do not need to set a specific offset, this is not a requirement for either HEC-RAS or RiverCAD.
If you have any additional questions or need any further information, please contact me again.
Sincerely,
Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com