I have a RCP 40 VS, so these tips are based on my experiece
Install and level.
Before turning on, check condition of rollers and gears. Try to move the gears of each module to see if they turn (they might be a little hard to move).
Next, fill all tanks with water. Don't put rollers in it yet. Check that there are no leaks, especially from the drain tubes. Turn it on (yes, without the rollers) and make sure the pumps are working and the motor is running (you should see the mechanical links where you connect the rollers rotating).
Check the temperature with a termometer in each tank. Do not trust the temperature scale in the knobs. It takes some time to get to the usual RA-4 temperatures (maybe 20 minutes).
There should be two buttons near the temperature knobs used to check if the working temperature has been reached or not. you may test it during this phase.
If everything works fine, turn it off and put the rollers into the processor. Now turn it on again and check that all rollers are moving.
You can try with a sheet of RC paper with emulsion side down. It may be a developed photo, just to check rollers are working fine.
Next, an important consideration. At least with the RCP 40, there where at least 3 models. One model did not have variable speed, another with variable speed and another with different tank sizes (a smaller one for Bleach/fix). So the important thing is to make sure you model can work fine with RA-4
If it has variable speed, then you shoud calibrate it so that developer time is correct (I think it is 45 seconds)
If you are going to process B&W remember that it works only for RC paper. Adjust temperatures and times according to your process.
The middle tank is for stop bath. Make sure you use stop bath and not water if you are going to use RA-4. Otherwise you may get color shifts.
The processor should have an inner cover for the tanks/rollers and the outher cover. Without the inner cover it won't be light proof.
Best of luck