The PCR can transmit program change messages, but Rapture doesn't support receiving them.
I can think of a couple of options here. If the Rapture presets that you're using are contained within a single Element or two, and you have less than six changes in total, then a 'custom' preset would need to be set up in advance. That is, copy and paste the core Elements to a single preset, and automate each of the six On switches or Mix knobs.
Multiple instances of Rapture could be pre-loaded with the appropriate presets, and you could 'fly in' the current sound with X1's mixing console. In this scenario, the PCR MIDI would be sent to all of the Rapture instances, and Sonar's controls could cover the selection / automation process.
I can provide more detail later on; depending on your preferred approach (if any).