We use an extremely distributed setup where DNS is completely handled of the remote side. So we serve DNS in combination with an extra smart-proxy for that DNS server. The DNS server handles forward and reverse zone currently without any delegation from an upstream DNS.
If we now configure the remote subnet with that smart proxy as Reverse DNS Proxy we get an PTR-Record because foreman uses the DNS-Server from its host machine to check for existing PTR records. The Nameserver from the foreman host also resolves the given subnet (private subnet).
Foreman should use DNS-Server for the reverse zone for checking for reverse entries.