Don't do it! Don't sign up with this company! If your child's parent won't pay child support, be patient. Work with your state child support agency. They have more tools to find the absent parent, and can do a better job for free.
I signed up for Supportkids, Inc. when my ex owed around $8K. I was already signed up through the NC state agency, but my ex moved out of state so they lost track of him because he was working under the table. My thinking was...some money was better than zero. But all Supportkids did was make phone calls to my ex's mom (he didn't live there, so that didn't accomplish anything).
Eventually a few years later he moved to GA, and NC state agency found him and started garnishing his wages. I was obligated under the contract to send 34% of everything I received to Supportkids, even though they didn't do anything to collect the money. They said that I would have to prove that NC collected it if I wanted to keep all of it, which was impossible since NC couldn't release his place of employment to me. For about 3 years I sent 34% of all money received from him.
Supportkids tried to get me to send the NC state agency their bank information so that my money would get directly deposited into their bank account. They started calling me and sending several letters telling me I needed to do so. I finally just stopped sending them 34%. They continued to try to collect from me by sending letters and calling me. After about a year of no money they sent me a letter saying they were closing my case.
The one positive thing of Supportkids is that it told my ex "I mean business". But it's just not worth it to sign up for this type of service. Don't let anyone get 34% of your child's money! Be patient, and let your state agency do their job.