help with cutting surfaces in soliworks! normal to the sketc

i’m trying to cut a slot in a curved surface. if i extrude a surface to split it then it cuts through straight along a direction.

i want the cut to be normal to the curve teh whole way around.
can anyone help me with this?

thicken surface, draw spline on surface (3d), create direction datum, cut.

its always hard to truly describe or communicate what you are trying to do sometimes in the program.

Seems like you could either extrude cut offset from surface. or project a curve onto a surface and sweep cut along that curve.

I do wish that sometimes Core would allow for at least scrreen shots to be posted