I have a windows box that we use for outgoing SFTP transfers. They're all scripted and I use PSFTP with PAGEANT to hold the private keys.
My problem is that over the last 12 months a new partner of this client has added a significant number of new connections each of which they insist upon having a new key pair for.
My problem is that now the connection that uses the last key in pageant gets 8 failed login attempts before finding the correct key on the ninth attempt. The admins at the other end of this have phoned us up and are asking what the problem is as their logs are flagging this as a failed hacking attempt every fifteen minutes, and they will automatically block the connection on the tenth failure.
I've read the putty/pageant documentation but can't see any way to force PSFTP to use only one key in pageant (a switch like -keyno x was what I was expecting to find)
I'm on the verge of re-creating the 'problem' connection and dropping its need for pageant entirely but that requires removing the passphrase from the keypair/including the pass phrase in the script. Whilst this is only sensitive rather than confidential data, we do make certain claims to our clients about security of connections and it includes language that suggests we follow best practice in these kinds of situations, so I'd like to not have to do that.
According to some of the documentation found here you can instruct PSFTP to use a PuTTY saved session instead of a hostname. You can specify the key specifically in the saved session and then as long as it's loaded in pageant then it will work as you expect it to.
EDIT:
Just read the link that you posted in your question and you're looking for section 6.3. That says that you can use an -i switch to specify a ppk file.