You might have to setup port forwarding on the VPN side in your account and/or in your VPN client software.
If you don't do that, you probably won't be connectible but everything will appear OK in your torrent client and on whatever tracker and website.
The VPN might assign you a port randomly, or you might be able to pick one. In any case whatever port the VPN gives you, enter that port in your torrent client as the port to use.
I forgot to do it with my VPN at first, but when I setup port forwarding my speeds improved tremendously.
Edit:@PIA:
Port Forwarding
Enable port forwarding in the application by entering the Advanced area, enabling port forwarding and selecting one of the following gateways:
Netherlands
Switzerland
Canada
Romania
After enabling port forwarding and re-connecting to one of the above gateways, please hover your mouse over the System Tray or Menu Bar icon to reveal the tooltip which will display the port number. You can then enter this port into your software.
Port Forwarding reduces privacy. For maximum privacy, please keep port forwarding disabled.
https://www.privateinternetaccess.com/pages/client-support/
