I spoke with Radisson CS about integration/linking of accounts. Here is what they said:

"At integration, we will automatically transfer any Radisson Rewards Americas points and Elite Night Credits to your account as well as your tier status to your new Choice Privileges account. You will see these updates reflected in your Choice Privileges account on that day. If you are already a Choice Privileges member, no new enrollment is needed. We will automatically transition your Radisson Rewards Americas membership to your existing Choice Privileges account upon integration."

I don't know how they will know the 2 accounts are the same... so I'd suggest everyone get their email/address/phone as close as possible.