As there is an ADF bearing setting available

I cannot find how to set the ADF frequency

 

any clues?

I believe the ADF radio is an optional feature on the real airplane..

I had already raised the same question :

http://forum.avsim.net/topic/409480-adf-frequency/

Since then, I have implemented the solution proposed by Bert, and it works !

I add that ADF is not only for local flights, as Bert suggested. You may wish to land on a specific airport where the only available tracking mean remains the NDB. Furthermore, I flew recently from Iraklion (Greece) to Malaga, over North Africa, from Tunisia to Algeria. Many radionav equipments are still NDB in Algeria. 

I often use the ADF to intercept an ILS path

Hey guys hopefully this helps, you can use a GPS as a legal substitute to track to or from an NDB as long as the GPS is IFR certified. Most approaches (not all) say NDB or GPS so long as it does not only say NDB then you can shoot the approach using the GPS.