Attached is a more general solution. I first create a datum plane offset from the plane you require the curve(s) from. The datum plane is located so as to intersect the face of interest. Next create a section curve. Then move the datum plane until you get as close as you need to the desired curve. Note that for a face with no inflextion but convex in both directions then the minimum distance is a point. For a surface with inflection you could get multiple curves.
