firewall rule to allow traffic only through vpn

Hi, I’m a new user and I need a little help to create a rule that allow traffic only through vpn, at least for some apps - I tried to force all the traffic through it but I can’t do even this…I’m not so practiced! -. I use a vpn service (swissvpn) to protect my privacy. sometimes it disconnects from the server but apps are still connected through my lan to the net with my ip. I want to block these connections and I think (I hope) that it’s possible to do it using comodo firewall even if I don’t know how. in particular I’m interested to make uTorrent stop working if the vpn connection fall down. Would you please give me some help. Thanks.