How do loft cut a 3d surface

Hi all,

I am stuck.

I have a 3d surface and I want to have this face cut through a block. I wan the surface to get bigger all around like a loft cut. But when I project my 3d surface to the face or plane of the block it does not  grow proportionally with the distance.

Maybe I am using the wrong command. All i want to do is cut along the profile to have an open pocket

Please look at the jpeg to see if it clears things up

Regards,

Jamie Lill

SolidworksParts And Features