I just wrote a blog article to help me remember the steps to set up remote SSH command access from CircleCI to a general VPS. I’m on Vultr, but this will work with pretty much any Linux host. I don’t do it enough to remember the commands exactly, so it is helpful for me to have it written down.
https://blog.jondh.me.uk/2018/08/creating-a-vps-deploy-key-for-a-circleci-build/
Feel free to start a thread and ping me if you have any trouble getting your own version working.