Hi @Jasper1. I'm not sure if you've seen this article, but it explains that our admins manage all reverse DNS records for GoDaddy IPs. It's not possible to add a PTR record in our DNS management. If you are pointing your subdomain to another provider (an IP that's not controlled by GoDaddy) then you'd need to contact that provider to configure PTR records. Hope that helps.
JesseW - GoDaddy | Community Manager | 24/7 support available at x.co/247support | Remember to choose a solution and give kudos.