Why didn't you direct him to me...?
Particle effects can be resized with relative ease, the difficulty scaling with the complexity of the effect.
Basically you just edit the texture size in the emitter, but you must also be careful of the following:
When resizing the effect take in to consideration:
1. the relative movement of the particles (when the particles are smaller they appear to move faster/less consistently and vice versa)
2. Any affectors affecting said emitter, specifically linearinflate. Adjust it to make it work better.
3. The affector SizeOscillate will override the texture size no matter what as long as it is attached.
4. emitter location, make sure that it is properly scaled with the size of the effect, as something that is off-center will need to be adjusted to fit better. Ignore this step if your entire effect is at (0,0,0) location.
Basically it is simple to do, but it seems somewhat complicated. Trial-and-error got me the farthest in learning Particle Forge, so I wish you luck.