If you are talking about flying RF Legs associated with terminal procedures e.g. STAR/SID or even RNAV(GNSS) approach, then these documents have the answers:
Aircraft approval is published in the Airplane Flight Manual in LIM-22 under "AIRWORTHINESS STANDARDS COMPLIANCE" paragraph.
Individual aircraft capability can be confirmed in FCOM/DSC-22 in the "FLIGHT PLANNING - LATERAL FUNCTIONS section.
RF Leg Training is addressed in FCTM/SI-110 (ICAO recommends “training” for RF Legs).
All of the above was only addressed by Airbus last year due to guidance from ICAO and FAA only recently published.
Many airlines do not publish their AFM for Flight Crew to see, so this needs to be addressed somehow e.g. on a placard or checklist.
RF Leg associated with RNP AR approach is subject to different approvals.