Return of Reckoning

Am I losing my mind or in unit frame is there no way to display enchantments such as Flames of Rhuin on unit frames?

There is simple way : got to unit frames > Effect indicator > create > fill with ID or name of your enchant > set icon and parameters such as size and position.

I set up multiple indicators for my runes, tactic procs, HoTs and such, it's very easy to do as long you know how to setup them.