Trouble with SSH key pairs windows client

Hi all, Trying to set up SSH key pair access to my droplet using PuTTy on Win7 and just about ready to open a vein :( Here are the steps I followed.

1. Generate key pair in PuTTyGen
2. Use the public key value in the generated key box and paste into authorized_keys on my server. (If you click save keys you get the PuTTy format.)
3. Conversions - Export OpenSHH key
4. Add this key under SSH - Auth in the PuTTy profile set-up.
5. Restart SSH on droplet
6. Try to connect in PuTTy. I always get Unable to use key file …

Is there not an OpenSSH utility for windows that creates compliant, industry standard key pairs out of the box?

Thoughts appreciated. :)