Netherrack Fuel?

[stormy_skies]

Hey, just a quick question about netherrack as a fuel source, since I can't figure out how to actually use it
I tried to place it inside the fuel slot in a furnace since the tutorials for the mod show it being used as a fuel source, and then tried to use coal to fuel the furnace and replacing it with netherrack after, but neither of those worked?

Can someone explain how this works? I'm super confused

[camoweed_]

Make sure it’s cobbled netherrack!