Have you looked at this page: Bitwarden SSH Agent | Bitwarden Help Center
What OS are you in? On windows it does not work with anything that uses pageant yet although there is a workaround that I am using: How to use SSH Key? - #9 by gooseleggs
Also be aware that there is a forum about having too many keys in the vault may mean that the connection is denied by the SSH server due to too many authentication attempts.
This is the first release of this so expect it to get better.