$ ssh-keygen -t  rsa

$ ssh-copy-id -i ~/.ssh/id_rsa user@domain
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
user@domain's password:

Number of key(s) added: 1

Now try logging into the machine...

check keys added

~/.ssh ssh-add -D
All identities removed.

~/.ssh ssh-add   

~/.ssh ssh-add -l
all keys
all keys
all keys