waveguide port feko

Hi everybody.
I need to exicite a ridged waveguide port in FEKO but I don't know how. I suppose that the AW card is just suitable to the conventional rectangular waveguide. I can't use the AP card too as the ridged waveguide has no simple field equations to be written in editFEKO. Besides I want the port to contain a match load (with AW this is done by setting the excitation amplitude to zero)
any ideas?