As you can see from the diagram above, the 500K Resistor is soldered to the Bridge connection on the Switch, and then soldered to ground. If you had a reverse setup, like a Single Coil in the Neck and aHumbuckerorP90in the Bridge, you would solder the 500K resistor to the Neck pick...
Seymour Duncan P Rail Review|Porter Wide Range Humbucker|Dual Coil Design:Features dual coils for a rich, balanced sound, perfect for Telecaster enthusiasts. Four Conductor Cable:Equipped with a four conductor cable for versatile wiring options and shielding. ...