ssh remote rsa key login (without password)

After changing my system to manjaro I had to recover some settings,
and sadly had to do some things again, e.g. my ssh login via rsa keys.

After doing it manually I saw this 3 step answer on some message board:

1. ssh-keygen
   Press Enter key till you get the prompt
2. ssh-copy-id -i root@ip_address
   (It will once ask for the password of the host system)
3. ssh root@ip_address
   Now you should be able to login without any password

One thing I had to change: chmod 700 .ssh on the remote machine,
and then it worked like a charme.