Use RPL within a CX App action step in Responsys

Hello Everyone!

We are in the process of developing a CX App for Responsys. Our use case requires to render personalization within the text before it is sent to the App we are developing. Is it possible to use RPL in a text in a CX App step?

If it is not possible, are there any guidelines that can point to the right path? Other option that we have explored was to retrieve information via API, but we can get only one record at a time with the primary keys. Our personalization requires to get data from supplementals according to criteria other than primary keys. So it can work up to a point when personalization comes from a single record.