Cartridge Loading into Step-Up Transformer

I have read a lot about preamps and phono stages having the ability to put a load resistor in parallel to the cartridge.  Some products have flip switches, others have solderable terminals inside the unit to put in a custom valued resistor and others have a pair of external RCA jacks to put a resistor here.  Mt preamp has the latter.  However, if an external  setup transformer is used into a MM input, what is typically done to accommodate a load resistor?  Is the resistor in parallel with the primary or the secondary?  And is the resistance value typically different for a given cartridge that worked well into an active MC stage vs. a setup?  Any experiences, ideas, suggestions, etc., would be greatly appreciated.
John