I am a bit confused whether RMI is supposed to show ADF. There is no change switch and manual only mentions VOR, but the markings on RMI suggest ADF too.
Fokker design choice. ADF needles can only appear on the ND screen for some models. JF model and some Fokker Tango and Alpha models have ADF 1 and 2 buttons which are to the side (depending on the Capt or FO seat) of the ALT source select switches
