^^^ yup, put the foil on the grill plate, but don't completely cover it. You also need holes for the hot air to circulate and the juices to drain away. weber do a disposable foil convection tray, about $12 for a pack of ten, they're a lot easier that foil, which reminds me I need to go buy some more. Also consider buying a roasting trivet. I cooked a pork roast a couple of weeks ago when my parents were up, afterwards dad was ballsy enough to tell mum my pork crackle was better than hers