match a vertex to the end of a line or circle.

or, put a point in a sketch on the part so it can be used to mate to your layout sketch.

keep in mind when your mating components, you have to lock down 6 degrees of freedom. 3 translation & 3 rotations. A point to point mate only locks down 3 translation and leaves the 3 rotations. This mate would act as a gimble.


BTW, I like this style of modeling, make sure that the sketch is labeled 'layout' and it's obvious to everyone. I've seen too many assy's that I can't figure out, this step, adding a layout goes a long way to help understanding your design intent.