I am using VPN service and I want to use it on Kubuntu. The process is really simple if your VPN provider gives .ovpn files.
When you click the "connect" button it should work.
If you get this error in /var/log/syslog
"The VPN service 'org.freedesktop.NetworkManager.openvpn' was not installed."
Then try to install "network-manager-openvpn" package.