As I mentioned in http://www.autorefinancing.us/t/keyboard-maestro-remote-web-trigger-works-on-mac/56/1 you can get a Custom URL on Mac OS to drive Keyboard Maestro.
However if I enter a URL to, say, http://www.ibm.com it has no effect when the button is pushed. This is true on both Mac OS and iOS.
So, when I press a button that is defined a Custom, with a URL what is it supposed to do? Pop up a browser window?
Actually on iOS I wanted to use a URL of the form editorial:// to kick off the Editorial app. Nothing seems to happen here. So workflow:// would be nice for kicking off on-device automation.