Someone w/ a like year KDX200 manual should be able to answer that for you. I have the KDX250 supplemental manual, but the section referring to spark plug gap says "refer to base manual". That said, when I replaced my plug I measured the gap of the old plug and it was the same as the new plug out of the box, so in it went and the bike runs with no problems.
BTW, I went with a hotter plug than stock. I think I went with a BR7ES, but I can't be certain without going out to the garage and digging around.