As of version 0.4.3 VPN Activator now support PPTP VPN alongside L2TP VPN. At the moment the application will enable both VPN methods on your Mac. It is up to you to decide which one you want to expose to the internet.
To expose a PPTP VPN access you simply need to direct all traffic on TCP port 1723 to your Mac running VPN Activator.
You can download a copy of the latest version of VPN Activator by following this link.