>What does it take to run a vfp app in a mac when it was built in a pc.?

If you build a .app file in VFP3 on the PC it will run fine on a Mac running VFP3 for Mac.

I created a simple .exe on the Mac using VFP3 for Mac which simply does a
Do main.app

That way you never have to recompile on the Mac (which is a real PITA).
HTH