I see lots of other schemes for various functions in RCApp, but not to get to SMS?
https://developers.ringcentral.com/guide/basics/uri-schemes
If there isn't one yet, I really think it would be nice to add something similar to this:
rcapp://sms?number=<phone number>
that would bring the RC app up to the conversation with the phone number, or if one doesn't exist start one.