Clicking the RSA Key button in the page VPN Configuration leads to the VPN RSA Key window where the public key is displayed in the text field RSA Public Key  so you can inform your VPN partner about it e.g. via fax. This page also allows you to generate new keys. If you want to do so, please keep in mind that these RSA keys always exist as a pair and creating a new public key also will create a new private key - and will shut down all existing VPN!