Fatwood is fatwood because the sap has settled in and dried. It’s not sticky at all.

If you want to start a fire with a match, you can whittle toothpicks of fatwood as a primary tinder.

If you want to start a fire with a ferro rod, hold the edge of your knife almost vertically against the fatwood and scrape. That will give you the fine shavings of wood you need. Make a pile of those shavings, and they will catch a spark and burn.