When establishing the stages of execution in a schedule, you may want to pull down the active virtual users at different intervals but may not find an option to do that in Rational Performance Tester (RPT).
You may also find the below Request for Enhancement (RFE) whose status may say the feature is delivered -
However, the RFE had been closed saying that the functionality was already available in the product.
The explanation is that "Change Rate" could mean "Ramp Up" rate or "Ramp Down" rate depending on the context.
If the current stage has more users than the previous one, "change rate" means "Ramp Up" and if it has lesser users it will mean "Ramp Down",
For example, the first stage may have 100 users and the second stage have just 1 user. The "Ramp Down" happens in the second stage.