I'm not sure if you mean file size or image size, but to answer both:
For file size, I just moved the quality slider down until it was under 35 kb (the forum limit)
For image size, I just used a 400x100 pixel canvas (the forum limit)
Meh, I'll get to the other sigs later, if Skillya, Bullet, or Spirrow haven't done them by tommorow. I had parent-teacher confrences tonight and I need to make up some work.