There is nothing special about your device keys other than the Private Key being stored exclusively on the mobile phone. Therefore in order to authenticate you must have the Desktop Agent software running, just like you may use the standard ssh-agent command line program to temporarily store your keys to save you having to use the passphrase every time you SSH.
So just like normal keys you need to place your public keys in each server's
To access the public keys you can download these individually from your key listing on the gateway service and use them to configure access to your servers.
You can also run the
authorizedKeys command on any device you have installed the Desktop Agent on.