I’m trying to create a Tor proxy for promotion and failed, so I’m reading the material trying to create my own Tor exit node, but I don’t know the DNS record settings.
How can this be set?
You can find reverse DNS settings in the servers hosting web interface and you have to configure it there.
You must use a domain that you own.
The rDNS domain should make it clear that it is a tor exit.
For example: tor-exit.yourdomain.xyz
It is important that in rDNS, not only the IP must point to the domain, but also the domain to the ip address. So create the A (and AAAA if you have ipv6) records for the domain name.
If you can tell which hosting are you using, I can help you with the setup or I can find the documentation for you.