Hi,
You could select all the layers after importing the HEC-RAS file in RiverCAD and move all the layers on top of the contour map.
Otherwise, you could import the contour in the existing drawing as an External Reference from the 'Insert' menu under 'CAD Drafting' module.
If you want to update your all the imported cross-sections based on the contour map then use 'Recut existing cross sections' after overlaying properly, by using contour as your elevation layer. It will automatically update all the cross-sections at one go depending upon the contour data.
Thanks,
Debajit
debajit@bossintl.com