need help.. child custody/support.. signing over his rights? desperate for answers PLEASE READ!

i was dating a guy for about four months and found out i was pregnant. he was barely there for my pregnancy at all. never paid for any hospital bills or appointments, and once the baby came he still has never done anything. never paid a dime on his own kid, never changed a diaper, ect.. he's only seen him a maximum of seven times (and my son is now almost 9 months). we both live in different towns... about 45 minutes away by car. i have not seen nor heard from him in over four months. he has not bothered to contact me, ask how his kid is, ect. my son has my last name.. but i was stupid at the beginning and signed the paternity papers stating that it's his biological kid. we haven't been dating for about four months now. he's a drug addict and is sleeping with a girl underage. i need help. i want child support because i need the extra money to help with my son.. but i dont want him to try and go for custody. i honestly dont think he would.. but this guy likes to ruin lives. i can imagine him trying to pull something. i just really need to know what my options are! i live in pennsylvania, so does he. what are my rights? could i get him to sign over his rights and have him still pay child support? or could i atleast get child support without him having a chance in hell to get any kind of custody or visitation?? please help. i'm so upset about this whole situation. i dont wanna lose my baby to him. my son doesn't even know him and the guy is disgusting.. lives in a bad environment. i know there is plenty of things i could say to the courts to prove him as a bad parent.. but there's no way to actually "PROVE" them. or is there? please please help. reply on here or email me at [email protected]... thanks so much.