If a man signs over his rights to his child does he still have to pay child support?

Depends on what is worked out with the courts. Opinion is that he should that's just my opinion.

If a man signs over his rights to his child does he still have to pay child support??
If you are in the US, there are laws in all 50 states that prohibit a parent to sign over his/her rights for the sole purpose to get out of paying child support.
Unless they are signing over their right so that the child can be adopted by someone else, they will still be required to pay child support.

I believe he can not get out of child support period, unless he shows it is not his child.. and even recently there have been case that men still have to pay.

Not sure what state you are in but take a look at the California site.

Publications (http://www.childsup.cahwnet.gov/Resources/Publications/tabid/86/Default.aspx)