A lot of people have been asking about using RL with Attract, so here is what needs to happen on the attract side of the house. This was posted by the RL Dev, it does not cover setting up RocketLauncher itself.
What you need to do in each Attractmode\emulators\*.cfg, open them all in notepad++ and change the executable and args to this:
executable D:\RocketLauncher\RocketLauncher.exe
args -s "[emulator]" -r "[name]" -p AttractMode -f "D:\AttractMode\attract.exe"
Obviously edit your path to your RL exe. When you do that, your RL log will show this:
Main - Raw CLI received: "-s Nintendo Entertainment System -r 1942 (Japan, USA) -p AttractMode -f D:\AttractMode\attract.exe"
One other important thing is the system names in Attractmode must match RL official names. So for NES, the emulator cfg looks like this:
Nintendo Entertainment System.cfg
It makes no sense to keep them the emulator names as what comes default with AttractMode as RL is now handling emulators, not the FE. Also, if you don't want to change the names, then you have to edit that -s "[emulator] to include the official name: -s "Nintendo Entertainment System".