I'm using Hydrogen and Gantry 5 on Joomla 3.4.3 without use a Rocketlauncher.
If I correctly understand, I should change my footer in each outlines. I can't have a master outline where I can change a default parameters.
However, thanks to Settings tab, I can manage some particle / atom like Google Analytics without having to change it in each outlines.
Lets say you had 4 Outlines and the first two you placed the Branding particle and then realized you neede to change it. So you go to Base Outline and make your changes to the Branding particle. You now add that to your last two outlines.
The result is that the first two outlines won't show the changed Branding particle but the last two will. You would have to delete the current Branding particles from the 1st two outlines and then Drag in a Branding particle which has your changes.