ShortPath is the command which creates the minimum length curve on a surface between two points. I don’t know if it currently available in Rhino for Mac.
InterpCrvOnSrf does not always create the minimum length curve on a surface between two points. It may create a longer curve depending on how the surface is parameterized.
The CurveOnSurface Plug-in for Rhino for Windows also creates the minimum length curve on a surface between two points.