is there a simple way to offset the surface to make a recess cut into the example …the normal way I would do this is to make a copy of the ring example and hide it. .then split the original ring with the curve then delete the split ring leaving the shaped surface. now .offset / solid / both sides of the surface…now bring back the hidden ring and do a booleon diff. leaving a recessed channel looking for that 'magic button to do this …
never mind …answer is ‘wire cut!’