there are 2 basic rat familys in general, wharf and roof rats. Roof rats like fruit/nut food. I use a commercially prepared attractant but believe you might find good results with FIG NEWTON bars, using the fruity gooey center for the attractant. It smells just like what I use.
Peanut butter and cheese works but it never hurts to vary your attractants. If a rat has had his nose or head popped unsuccessfully by a trap but didn't get caught, he won't go back that THAT attractant again, or even a trap that smells similar [wood trap such as a Victor]. If you've used wood traps for a while, switch over to plastic traps such as the T Rex brand. They smell different and rats are smart and have memory. Also, make sure the traps do not 'move' easily and are set on a surface that does not let them 'wobble' when touched. Rats want a quiet secure surface to first explore, not something that 'moves' or feels insecure.
From a rat chaser for the last 40 years.....and still doing it.