PTR records, also known as reverse DNS records, link an IP address to a domain. The records will have to be added by the provider of the IP addresses, not by OpenSRS.
For example, you might have purchased the usage of an IP address from your internet service provider. The internet service provider will have to add the PTR record for you. After making the request, you can double check your domain by going to a configuration checking website such as www.intodns.com. If the record is setup correctly, you will see the following: