Contents of .ssh/config,

# Host myshortname realname.example.com
# Hostname realname.example.com
# IdentityFile ~/.ssh/realname_rsa # private key for realname

Host serveradmin.earth
Hostname www.earth.com
IdentityFile ~/.ssh/serveradmin_rsa_204.www.earth.com

Make sure when connecting to specify the host and your id if it is the not the same id as your client Unix account. For example, if the user was logged in as Brian Hitch (bhitch),

ssh svradm@svradm.lemonbistro.com