I may be wrong here, but I understood that a rising rate reg did the opposite.
A factory reg runs a 1:1 ratio between boost and fuel pressure, so for each psi of boost, the regulator increases the fuel pressure by 1 psi.
A rising rate reg runs 1:1-and-a-bit boost:fuel pressure, so for each psi of boost, the regulator increases the fuel pressure by say 1.1 psi. At higher fuel pressures, more fuel is injected at a given injector duty cycle. This is to stop the A/F leaning off at high boost levels.
The advantage of rising rate reg is that they can be adjusted to give a different-from-factory base fuel pressure, say 45 psi at idle instead of 40psi at idle. This is a cheaper way than fitting a set of higher capacity injectors.