The father of my son is denying the fact that he is the father and is having no contact with me during the pregnancy... I am wanting to know if after the baby is born and he is proven to be the father by a paternity test, can I make him sign over his rights or does he have to do it willingly? We are residents of WI

I don't think you can make him sign over his rights.
But you can establish he is the father and get support for the child that the child deserves.

Get a lawyer on that now is my advice.
Visitation (if he wants it , he should have it, if not, no worries) should be spelled out
Along with the order for support. On the court documents. No arguing with court orders.
And if he signs over his rights, it does not affect the child support. He will still
Be responsible for support.

Hopefully he will man up and want to be a part of his child's life .
Even if you hate him, as long as he is not a danger or negative influence to his child,
It is better for the children to have both parents love and take part in their care.

Please pay more attention to posting guidelines. There is a Read First sticky in the Children forum (where this was moved from) that directs questions of a legal nature to this forum.

Had you looked for the proper form you might have found this sticky Note: https://www.askmehelpdesk.com/family-law/signing-over-rights-read-first-116098.html

Which would have answered your question. Only a court can terminate parental rights and courts are VERY reluctant to do so. I don't see any reason why they would do so in your case. What you SHOULD do is file for custody and child support as soon as the child is born. This will require a paternity test to establish legal paternity.