There are a number of folders which can accommodate 200 pounds. That's not really your problem. Your problem is that you are 6'4". You're going to have a problem with reach.

Most folders are one-size-fits-..., well, short people. They don't have a proper reach for anyone your size. To put this into context: Bike Friday, which makes folders properly sized to fit you, makes the Tikit in sizes small, medium, and large. You're definitely a Large. But... the Brompton is slightly shorter reach than a *small* Tikit. And most Dahons are about half-way between a small and a medium Tikit.

To make matters worse, a great many folding bikes don't permit modification to their ahead stems so you can't easily customize the reach. At best you can push forward an inch or two with custom aftermarket stuff like the AberHalo on the Dahons. And some, like Bromptons, don't even permit you to change to more sensible handlebars. These are the compromises you make in order to fold.

This isn't to say there aren't tall people who haven't adapted to the size constraints of a folding bike. But at your height you'll be so upright that you may want to give this another thought. I have a friend at 6'3" who rides a Dahon P8 with an AberHalo stem and just grins and bears it.

Bikes which will likely fit you: a Tikit (or other Bike Friday). A Montague. Maybe a Swift? A Dahon Vector P30 with a custom-length stem perhaps?