So, what it does is do the automation for you automatically between some parameters that you give it. So you would set a range, shown on the left below, that's you telling the Vocal Rider that you want it to write automation so that everything falls between that minimum and maximum:
Here's the manual.
The Rider slide in the center is just what it sounds like, it's the same as if you had your hands on a fader and were riding the volume yourself, it does it automatically based on the minimum and maximum you told it to do. That Rider shows you what's happening.
The Output there is a boost or cut depending on what you feel you need at the end.
And on top you'll see the Target slide, that's you telling it where you want it to sit in the mix, if you want it to be the loudest thing for instance you could set it to -1dBFS (zero is the absolute highest it could be) and then have every other elements in your mix be quieter.
Since what the Vocal Rider is doing is writing automation into your DAW for you automatically, you can go back and edit the automation later if you wish using your DAWs usual capabilities. So, yes, if you wanted it to swell in the chorus, you could still go back and write in your own automation to make that happen, of course you would want the Target to be set to something like -4dBFS otherwise you would not have any room to increase the volume to.
It's a great tool.