Well, RailClone surface tools are a little limited at the moment. Rather than follow the polygons or the UVs like a paneling tool, in RailClone geometry is projected along the RC object's local Z axis until it hits the surface's geometry. This means that it only works well when the face normal points towards the RC object.
"Extracting" (for example by the Create Shape
tool in the Edge
mode) & using X & Y Splines from such a surface would be the recommendable way.
An option might be to use the SlideKnit script (mentioned in this post
), which allows you to flatten the surface, apply the high poly object and then morph the surface back to its original shape, deforming the geometry in the process. You can read more about it here: https://simonfuchs.wordpress.com/2014/08/17/tutorial-adding-detail-to-your-highpoly-objects-using-the-slideknit-script/