Actually, Road Force Balancing is not intended to reduce the number of weights on the wheel. In fact, it may actually result in more weights being required. The purpose of RFB is to reduce vibrations that are not caused by mass balance. Those vibrations result from two sources, which the RFB machine measures and the technician may try to resolve by rotating the tire on the wheel and / or swapping tires around on different wheels. The two sources are out of round tires and / or wheels plus variable spring forces generated by the tire.
This all sounds great, but there are two big issues. First, new tires and wheels are made to very precise tolerances, thus making this extra effort usually unnecessary. And second, it is a well known fact that very few technicians will actually dismount and remount a tire based on the RFB results. Therefore, the RFB typically ends up becoming a Road Force Check. Which means you pay more, but don't end up with any significant advantage for your money. Unless you are trying to troubleshoot an actual vibration problem, I would suggest saving your money on the Road Force Balance.