I have never had this much trouble connect to a website...I confess I'm a newbie to DO - their support has been rather "catty" in offering assistance...but here's the details of my adventure:

I've created my keys per these instructions - https://www.digitalocean.com/community/tutorials/how-to-use-ssh-keys-with-digitalocean-droplets

I've set up FileZilla according to the instructions here - https://www.digitalocean.com/community/tutorials/how-to-use-filezilla-to-transfer-and-manage-files-securely-on-your-vps

09:49:22 Status: Connecting to 198.199.70.226...
09:49:22 Response: fzSftp started, protocolversion=8
09:49:22 Command: keyfile "/Users/Donna/.ssh/idrsa"
09:49:22 Command: open "root@198.199.70.226" 22
09:49:23 Error: Disconnected: No supported authentication methods available (server sent: publickey)
09:49:23 Error: Could not connect to server

After many attempts to add my public key to an existing droplet - via my Terminal when I try command - ssh root@198.199.70.226

I keep getting:
Permission denied (publickey)

I've added my public key via DO Console to the ~/.ssh/authorized_keys file. I've restarted the server using "sudo service ssh restart"

Any support would so be appreciated!
Donna