Find a formula for the Necrophage Oil in Flotsam

In the Witcher 2 the storage system do not belongs to Inn keepers but some other people. Like for your case in Flotsam, the storage is set to a man down-stair sitting inside a bar or walking around it. (just left turn when you enter the room with fighting area) And in Act 2, is the dwarf walking around or sitting in front of the whore camp's fire.

You can use the Cat potion to easily see the blood trail in the forest. There are at least three trails to follow, all starting near the gate between Lobinden and Flotsam. By keeping (mostly) to your right, you will end at human corpses. But if you try to keep to your left, Geralt will mumble something about "he is getting weaker, can't be far now." That trail also ends in someone else's body. But from there turn around and keep to your left again. Cedric is not far from there.