http://oi45tmbel5syg4uet4t2fg6ipfu22ewfb4dfgpeckarn3qtv3pwq.b32.i2p/tips.html
As for why I don't include this option in my connection scroll, the reason is that my server's set up not to accept any authentication mechanism, and your client will notice this and not offer public keys at all (run it with -v and see for yourself: you may see 'Will attempt key', but you won't see 'Offering public key').