In case of a complete reinstall or just moving to another computer, and you have RSA access to servers they need to be imported to your keychain. It is up to you where you keep your RSA certificates. Keeping them in .ssh folder is an option.
Open your Terminal, and if you have your certificates in .ssh in your home folder, here is an example.
ssh-add -K .ssh/id_rsa
You should now be able to access your servers again with the RSA certificates.
Happy certification!