First, may I offer some tips on using this site. Before you jump in and post a question it pays to browse around and look at all the forums that may be pertinent to your question. For example, if you had looked further down the list you might have noticed the Family Law forum (where I moved this to from the Children forum). Since this is a question about law and not about child rearing, it belongs here. And you also might have noticed this sticky https://www.askmehelpdesk.com/family-law/signing-over-rights-read-first-116098.html. Reading that would have answered your question.

You see you can't just give up your rights. Only a court can issue a TPR (Termination of Parental Rights). And courts are very reluctant to do so. State laws do vary. In some states a TPR terminates both rights and responsibilities, in others, just rights. But the question is moot because a court will not issue a TPR if it lets the parent out of paying support.

So I'm not going to look up the law in PA whether a TPR terminates both because there is no way a parent will be allowed to give up their rights if it means the custodial parent can't get support.

And if for some reason ( other than adoption of the child) the court will allow you to give up your rights, yes you still have to pay support.

But you can't just give up your rights, and seldom will the court allow rights to be given up even if both parties agree.