You have to turn both ;)
The little one is the fuel adjustment. Turn out(CCW) for more fuel. The bigger screw is the 'bypass' screw, which controls how much of the air/fuel mixture is allowed to bypass the throttle plate at idle. Turn out(CCW) for more air/fuel at idle.
Start with the choke full open. Loosen the screw on the throttle arm until it clears the choke cam. Then turn it in until it just touches the fast idle cam and then turn 1/4 turn more. Lightly bottom both screws on the side of the carb and then turn them both out 3 turns.
Start the engine, warm it up if you haven't already. Check/set ignition timing and dwell. Adjust idle speed to about 850 rpm using the big screw. Turn the smaller screw in slowly until engine speed begins to drop, then turn smaller screw back out about 1/4 turn. Reset idle speed to 850 rpm if needed using the large screw.
That should get you pretty close to perfect. Granted, if you are leaking air around the throttle shaft you can ignore all of the above, as your engine will never idle correctly with an air leak. Send the carb body in to Rimco in CA and have the bushings replaced, then give it a cleaning and put a repair kit in it. How to check for an air leak, you ask? With the engine idling give the ends of the throttle shaft a shot of carb cleaner in the space between the throttle arm and the carburetor body. If the idle speed changes you have an air leak.
Good luck with it.
Chris