Mark your guide target
Add a raid marker to an unmarked target selected by the guide targeting button, when permitted.
Settings → Automation → Mark the target
Add a raid marker to an unmarked target selected by the guide targeting button, when permitted.
Choose your setting
Open Settings → Automation → Mark the target.
Use it while you play
Add a raid marker to an unmarked target selected by the guide targeting button, when permitted.
Adjust it when you like
The guide targeting button must be enabled; marking also depends on game permissions.
Questions
Can I change this later?
Yes. You can change the setting whenever you choose.
Does it replace an existing raid marker?
No. It can mark an unmarked target selected through the guide targeting button when permitted.
The add-on is out now.
A free alpha for WoW: Forever. The app for web, iPhone and Android is coming soon.