That's not how proxifier is designed. Proxifier works per application and all traffic from OSBuddy is exactly that, from OSBuddy. There are no background services or other executables running which could be leaking his IP. Basically all traffic per application goes Application -> Proxifier configured proxy -> Server.
@DoubleD I suspect the proxy you're trying to use is faulty, but proxifier seems to think it's valid. Here's an easy enough way to verify:
If you haven't already, google "Proxy Checker" and run it through a legitimate looking site, or just ping it through command prompt and see what happens. If it times out, you need a new proxy.
Check your actual IP on a site like http://whatismyipaddress.com/
Log in and out of OSBuddy with proxifier as it's set up, verify that the "last IP" is set to your proxy IP
Log in and out of OSBot as standard, if you see your actual IP, with a different one in OSBuddy, you're good to go.
As an additional step, it may be worth checking your proxy's IP address against http://whatismyipaddress.com/IPHERE to see if it's already listed as a suspected/confirmed proxy.