You can modify any of the existing .rules file, or create a new file, say, 60-rayshobby.rules. It doesn’t matter which file you choose to append the new VID/PID pair.
Look, when I published the instructions, I had every intention to make it complete and clear. As this is an open-source project, there are frequent changes and it’s difficult for me to keep everything organized and updated at all times. I have a day-time job and I work on this project out of good will. If you encounter a problem, I encourage you to Google it, or just post it in this forum and I will try to answer it as quickly as I can. Expressing your frustration and venting that the instructions are incomplete doesn’t help much, and adds more stress on my side. It’s never my intention to keep the instructions incomplete. It’s just the nature of these projects that there are always unexpected problems and issues, and sometime barriers that require you to learn. I hope this is understandable.