Simply scrape tool with any knife to create small magnesium shavings. Then ignite shavings with built-in sparking insert, which is guaranteed not to separate from the magnesium bar, as to cheap imitations. Under windy conditions, the magnesium shavings should be placed in a depression in the ground. Tool will ignite rubber, such as from a spare tire, to create a distress smoke signal. Smoke will alert aircraft as to your location for rescue.
Gasoline is to hazardous to use but kerosene and diesel fuel are acceptable in emergencies.