Just curious, how would you constrain this and why.
Would you select the edge of the Boss or use Convert Entities first and constrain to that result?
Or would you draw a construction line that is co-linear with the edge and constrain tot hat?
Is it possible to constrain the sketch line to the face rather than the edge?
Sorry if this seems very trivial to you.
I'm trying to get back to basics and understand which approach is most stable.
The best approach is constrain to the edge. Convert entities or the construction line method is just an extra unnecessary step that would be relying on the edge anyway. Best to use the existing geometry instead of repeating yourself. You can't dimension to the face.
Hope this helps
Martin