Using a recovery code

I’m trying to set up the recovery codes preview feature. I’ve been able to get it to show the generated recovery codes screen to users after OTP setup but not sure how to give users access to using a recovery code?

The only mention of recovery codes in the documentation seems to be this Server Administration Guide but it doesn’t explain the full setup.

Addition info:
Using a custom browser flow with step up authentication

In case someone is still looking for an answer to this question…
Here is one way to allow the user to use the recovery code as an alternative to the OTP code.

The login process for the user will be as follow, provided that he has both OTP and recovery codes setup: