A simpler(?) explanation would be that the VTF spring acts on the back (counterweight) end of the arm. When set to "0", the spring is applying maximum force helping the counterweight to balance the arm. When the appropriate tracking force is dialed in, e.g."2", the spring force is released from the counterweight end allowing the cartridge end to become heavier by that amount. When the maximun tracking force is dialed in, the spring tension is totally released from the arm (along with any potential resonances). Rega's strategy of balancing the arm with the spring aiding the counterweight and then setting VTF by releasing spring tension is the opposite of most other manufacturer's strategies and everyone's common understanding, thus, the confusion.
I hope this helps.
I hope this helps.