Feeding 2.5 kg fondant slab in November — directly over the feed hole or straight onto the frames?

Second year keeping bees in Galway. We had a dreadfully wet October and my lightest colony feels like it only has about 12-14 kg of stores total, which I know won't get them through until March. I bought commercial Ambrosia fondant slabs (2.5 kg). Is it better to cut an X in the plastic and invert it directly over the central hole in the wooden crownboard, or should I take the crownboard off, lay the fondant directly over the top bars right above the cluster, and put an eke/empty super around it? I'm terrified that if cold weather hits (we get down to 1°C or 2°C at night now), the cluster will be too sluggish to break formation and move up through that little feed hole to reach the food.