From Birnam Designs Wiki

This is particularly useful with SSHMenu

when adding don't forget to prepend with username, e.g. root@1.2.3.4 (if it's not your username!)

ssh-keygen -t rsa

enter password, and save to a file e.g. ~/.ssh/id_rsa_domain

then move to the server with:

ssh-copy-id -i ~/.ssh/id_rsa_domain.pub root@1.2.3.4

You can add a non-specific id like this:

ssh-copy-id root@1.2.3.4

this will open a new session, enter password again