how to add an extra MFA method to an existing user flow

In our azure AD b2c tenant, we have an existing user flow with "SMS or phone call"开发者_开发技巧; as the MFA method. We want to add "Authenticator app - TOTP" option as well so that the users can select a preferred MFA method when they sign in. Can we achieve that by adding custom policy XML files from https://github.com/azure-ad-b2c/samples/tree/master/policies/totp/policy? Or can we just add another user flow with "Authenticator app - TOTP" as MFA method?