I wrote this for the tech manual of World War II Online (when it was called that):
"Targeting the engine deck was effective as blast and/or hot gases could pass through the cooling grills and enter the engine compartment, where fuel fumes might ignite. Such a result would most likely destroy the engine and the fire could detonate on-board ammunition and brew up the tank."
"Lucky hits aside, satchel charges proved most effective against tank tracks. Placed in or under the track, they would break the track and probably damage running gear. In most cases, these immobilized tanks retained their armament, becoming, in effect, pillboxes. If a satchel landed anywhere else on the tank, it would have little chance of doing serious damage – perhaps minor fittings, aerials, and the like might be destroyed. With luck, a sub-optimally placed satchel charge might produce spall inside a tank, concuss the crew, or injure someone directly opposite the detonation point."
"During the Winter War, Finnish General Headquarters studied the effectiveness of its anti-tank kasapanos (piled charge). It noted in February 1940 that 1.0-2.0 kg (2.2-4.4 lb) of TNT was sufficient to sever the track of a tank if blown under or next to the track. A charge of 2.0 kg (4.4 lb) could destroy vehicles of around 6 tonnes, 3.0 kg (6.6 lb) was sufficient to destroy 12-tonne vehicles, and 4.0 kg (8.8 lb) was sufficient for 30-tonne vehicles such as the Soviet T-28 medium tank."
"According to the Finns, 6.0 kg (13.2 lb) of explosives was powerful enough to knock out any Soviet tank of 1940 vintage, provided a soldier could get close enough to place it where it could do damage, on the tank’s rear deck. Destroying a tank with a satchel charge any other way was extremely difficult, as the charge could not be tamped and so much of the explosive force was lost. Some success was scored by soldiers who lay in trenches and allowed a tank to pass overhead, then secured explosives to the weaker underside armour of the tank with adhesive. When this worked, it would incapacitate the crew with over-pressurisation rather than disable the tank itself."
And my all-time favourite tactic, yet to be modelled:
"'Military Training Pamphlet No. 42: Tank Hunting and Destruction', a British Army publication produced in August 1940, included even more desperate measures. It suggests that a team of four can take out tanks with a length of railway track, a blanket, a bucket of petrol, and matches. The team was to hide in an alleyway or alongside a house where the tank is expected to pass. Two men hold the railway track with the blanket draped over it. As the tank passes the hiding place, these two run out and jam the railway track into the tank’s suspension. The third man throws the bucket of petrol over the blanket, now entangled in the track, and the fourth sets it on fire. Another plan from that booklet is for a single man with a hammer and hand grenade to station himself near the expected route of a tank. When the tank passes, the man is to jump onto the passing tank and pound on the turret hatch with the hammer. When the tank commander opens the hatch to find out what is going on, the attacker is to drop the hand grenade inside. There is no record of these tactics ever being attempted."