ssh-copy-id specifying which key and without password

Solution 1:

You can pass ssh options with -o:

ssh-copy-id -i mykey.rsa.pub -o "IdentityFile hostkey.rsa" user@target

Solution 2:

Yes, it is possible something like

ssh-copy-id -f -i hostkey.rsa.pub user@target

with latest version of ssh-copy-id. If you have some older, it might or might not work (with RHEL7 and older Fedora with SSH_COPY_ID_LEGACY=1 environment variable)