However many people you damage with the [Force] spell.
If the target takes damage, fails its saving throw, or is moved by your force spell, make a trip check against the target, using your caster level plus your casting ability score bonus
This is the only relevant rules text. If you have a spell with the [Force] descriptor, and the Toppling Spell metamagic applied to it, and you cast that spell, any target that takes damage, that fails a saving throw, or that is moved (a defined rules term) by the spell, is the target of a trip attempt.
It doesn't matter whether you damage them via missiles or lasers or emanations or using Havoc of the Society. It doesn't matter whether they are making saving throws against mind control, sneezes, falling over, being entangled, whatever. It doesn't matter if you're moving them with a [Force][Teleportation] spell or with Bigby's Bullrushing Hand or whatever. If the triggering conditions are met, you make a (aka, a single) trip attempt using different modifiers than the normal trip attempt uses.
It doesn't matter how many times you damage, or how many saves they fail, or whatever. All the effect requires is a single instance of any of those things, caused by a force spell, and then it makes a single trip attempt. There is no point at which multiple trip attempts would be made unless there are multiple targets, by the wording of the ability (if the target [..] by your force spell [...] make a trip attempt) and the usage of the 'or' list.