Automated formwork finish onto base of floor slab

I am looking to create forwork finishes for my slabs in recit. I have seen a lot of examples when creating floor finishes to use room boundaries this is not suitable for me. However is there a way in which i could use the surface perimeter of each slab and then use that to place the floor finish on the slab. any suggestions of example workflows would be greatly appreciated.
thanks

i am am being currently shown a branching error in the by outline node

Hello, I would try with the edges of a picked face rather than with whole elements because you are now selecting all possible edges

hey thanks for the advice.
came up with this as a simple solution which worked for me. dont want to be selecting the faces directly in Revit.

im going to try and look for a way to produce formwork on visible sides of the slab excluding the top surface.

thanks for the speedy reply