1. Go to Orders → Dedicated Servers / VPS Hosting, then open the settings of your order.

2. In the settings, go to the Network tab.
   
   

3. Select the Edit option in the Reverse rDNS Record field.
   
   

4. In the window, choose the IP address, fill in the record field, and click Change.
   
   

5. Done — your record has been applied to the selected IP address.

Order a VPS server: https://rx-name.net/vps
Order a dedicated server: https://rx-name.net/dedicated