I use 'Round Rectangle Tool' to create a rounded rectangle shape.
I want to apply dark gray border on the right and bottom of a rectangle shape (layer).
What is the solution to do this? I have tried to play around with Stroke (Position: Inside) from Blending option but no luck.
You could use for example Inner shadow to do that.
Other potential Layer style ways of doing that would be: Drop Shadow and Bevel and emboss
Here's a bottom right border made with Inner shadow:
And Those other mentioned Layer styles would also go by same basic idea. ( With drop shadow you could make a border that is set outside. )