here's how its done
Heal: You must heal the equivalent of 100 points of health. Meaning you can't get a heal point off of one soldier.
Ex. I see two soldiers. Each soldier needs 50 health points. I toss 2 medpacks and they both pick them up. I get 1 heal point.
Ammo: You must refill one of the weapon's spare magazines up to full.
Ex. I shoot a bullet. You toss me a ammo pack. I still have all my magazines for my gun, so I don't pick it up. Then I reload the gun. Suddenly I'm down 1 magazine, so I pick up the ammo pack, and you get an ammo point.
Ammo is insanely easy, because it only takes 1 gernade toss or 1 anti tank shot to merit reloading, and thus ammo points. An easy way to get ammo points it to play US on karkand and at the very begining when everyone is tossing nades over the fence, chuck those bags left and right. I have gotten several points there before because of that tactic.