Press plane in to existing surface

[joshpigford]

I've got a vertical rectangle that's place over the side of an uneven shape.

I'd like the inside of that rectangle to basically be even with that shape.

I'd initially thought about somehow adding some "points" the the rectangular plane (much like you might do in a program like Illustrator) and then press/pulling those points in so they match, but could never figure out how to do it. And there may be an entirely easier way. ¯\_(ツ)_/¯ 

I've attached my f3d file.

[Anonymous]

You mean you want this vertex and the right vertex on this edge to be coincident?

If thats the case, I would probably try to create two planes (one at each side) that are parallel to the XY plane and that intersect this vertexes. Then, you can use those planes to split the body and I think you might get where you need. 

[chrisplyler]

When you make a sketch plane flat along that irregular model, on which to draw your rectangle...

First project all the irregular edges onto the sketch plane. Then draw the other three sides of the rectangle as you normally would with the Line tool.