If you want to use Advanced Capability of Spark, open a Custom HotKey editor.
You can open a Custom Editor by double clicking on "Custom List" icon or opening a Simple Key Editor and the switch to Custom Editor ().
When creating a Custom Key, you will first have to choose a keystroke and a name. After that, you can create couple of Application/Action.
In this example, when iTunes is front Application, the Action will be Play/Pause, else if the frontmost application is one contained in the Graphisme Application List, Spark will be ignore and the application will act as if Spark doesn't run, else if front application is an other Application, executed action will be iTunes.