Its quite cake actually.
1. Get proxies to .txt
2.Open PF and go to Open proxies
3.Press add proxies , import and choose your txt file and press ok, now you will see all proxies there.
4. Press check proxies (on Open proxies page) and run proxy check ( I use default setting o_0) after its done press ok.
5. Now you will see all proxes that worked, delete the ones you dont need.
6. Go to rules, choose program and click edit , choose your option from popup which comes . we assume you want use single proxy so click that button and you will find your proxies from open proxies\sock or w/e proxies you were gathering, easy as that if you want change do 6. again