In general, if you are able to access an HSM device via .NET's
RSACryptoServiceProvider, Rebex SFTP and SSH classes will be able to use them. Pass the appropriate instance to the relevant
SshPrivateKey constructor (see here for details) and chances are it would work.
However, in practice, things can sometimes get more complicated (PIN codes, different vendors, CSP provider bugs, etc.), so we strongly advice our customers to make sure we are compatible with their HSM devices of your choice before making any decisions related to this.