How to create a SSH key for RocketGit:
cd; mkdir -p .ssh; chmod go= .ssh
ssh-keygen -t rsa -b 4096 -o -C "Key for RocketGit" -f ~/.ssh/rocketgit1
or
ssh-keygen -t ed25519 -C "Key for RocketGit" -f ~/.ssh/rocketgit1
cat ~/.ssh/rocketgit1.pub
Now, copy in clipboard starting with "ssh-...", including the comment and paste it in the form above. Do not worry about spaces or wrapping.

To force the use of this key when you connect to the server,
add the following lines to your ~/.ssh/config (use tab to indent):
Host @@rg_ssh_host@@
   User rocketgit
   Port @@rg_ssh_port@@
   IdentityFile ~/.ssh/rocketgit1

Then, protect the config file:
chmod go= ~/.ssh/config

To see the fingerprint of your local key (for comparison):
ssh-keygen -f ~/.ssh/rocketgit1 -l