How to pass session to KITTY, but using SSH-key, not Password-based

At this moment, we can integrate & open the sessions in PuTTY. But when we followed exact steps described here:
https://winscp.net/eng/docs/integration_putty#kitty
it does not work if we connect to site with SSH-Key based authorization inside WinSCP, and then try to open the session in KiTTY.

Any help?

There are two ways to configure KiTTY in WinSCP:
1) With use of registry – In this mode all relevant settings, including the key, is transferred to KiTTY.
2) In portable mode – In this mode the key is not transferred. But you can load the key to Pageant to make it available both for WinSCP and PuTTY/KiTTY:
https://winscp.net/eng/docs/ui_pageant

Many thanks, for the case of portable use, I'll look into Pageant docs. Hope it's easy instruction to do.
But why WinSCP doesn't have a simple way to pass the ssh-key location by parameter to PuTTY? So, avoiding the Pageant middleman.

Well, there are so many things that can be improved. And there are the two solutions for the problem mentioned above.