I have Putty, and it is configured to use my key.
You may know that you can create and save a "profile" w/ putty, and I have profiles saved for all servers. So, when running Putty (or Plink) you just reference the saved profile on the command line, like:

putty @profilename

I assume when you say ...

Can I configure Zeus to use my public key for authenticating sftp?
My SSH servers are all configured to refuse passwords.