If you want to set up a new fingerprint for your Smart Lock R20, you can follow the steps below:

1. Go to your lock's page and connect to your lock.

2. Go to "Manage Access" at the bottom right corner of the screen.

3. Find the person you want to add fingerprints for and tap it. If you have not given access to that person, tap "Add Access" and follow the instructions to create a user profile first. 

4. In Access Info, tap "Fingerprint".

5. Now you can add new fingerprints.