I understand how two woofers would be wired up ( either series or parallel ) depending what ohm rating one is looking for

so how are three woofers wired up? 

They are generally wired in parallel, but with different network elements feeding different drivers.

http://www.jblproservice.com/pdf/JRX%20Series/JRX125.pdf

can someone explain how the RF-83 or RF-63 has them wired up?

In a UREI (JBL) studio monitor only one of the three woofers runs up to the crossover point for the HF horn, the two other woofers roll off at lower frequencies to avoid interference in the midrange.

http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-815.pdf

This is the same idea behind the two woofer JRX series, and Klipsch probably does something similar (for similar reasons).

The Klipsch is probably a simple network like this JBL 4612:

http://www.jblproservice.com/pdf/Network%20Schematics/4612OK%20Network.pdf

As we can see, one 8" woofer runs up to the HF crossover point, and due to its natual roll-off has no crossover parts. The other identical woofer has a simple lowpass filter so it can't interfere in the midrange at the crossover point. The simple HF crossover for the horn resembles a Klipsch network with its tapped autoformer to set the HF horn level.