Create a surface in the model that represents the contact area of the bearing race and shaft. You can then apply the load to that region when defining the boundary conditions.
You can copy the outer surface of the shaft and then trim that to match the bearing interface.
You can add a surface region to the OD from within Simulate. This way you only modify the geometry as part of the analysis only. Look for the tool that allows you to create a "Surface Region" from within the "Refine Model" tab:
Make sure you also use the "Bearing" load option so the load distribution will be more realistic.
