Using the Helldivers 2 Supply Pack on yourself isn't especially intuitive since there are no clear button prompts, but you just need to tap the D-Pad or follow the resupply button prompt for teammates. The Supply Pack is also one of the best backpack Stratagems to use if you don't have the Warp Pack or don't fancy a heavy weapon with its own backpack ammo supply, so it's good to know exactly how it works and how to use it in Helldivers 2.
