Before you can use openssh transfers (sFTP and rSync over ssh) you need to prepare the Home folder, and accept your server's host key.

(replace server.domain.net with the dns name / ip address of the server you want to use)

Open a command prompt, and browse to the Six Updater\tools\bin for rSync, or Six Updater\tools\cygwin\bin for FTP, then:

ssh server.domain.net

If you receive an error like: Could not create directory '/home/SB/.ssh', press ctrl+c to cancel and manually create the folder mentioned after /home/,  into the tools\home for rSync, and tools\cygwin\home for FTP.

 In my case that means creating  Six Updater\Tools\home\SB

If the command is succesfull, the output should be as following:

The authenticity of host 'xx.xx.xx.xx (xx.xx.xx.xx)' can't be established.
RSA key fingerprint is xx.xx.xx.xx.
Are you sure you want to continue connecting (yes/no)? >>>>> ENTER yes  HERE <<<<<<<<<<
Warning: Permanently added 'xx.xx.xx.xx' (RSA) to the list of known hosts.

Enter yes, press enter, and press ctrl+c to cancel.

You're now ready to use the host: server.domain.net

Don't forget to specify your SSH private key in the software. For openSSH the private key should have NO file extension.