I won a H&R Handi Rifle in .243 at a local gunshop raffle.

It has no iron sights, but comes with a weaver rail. I was thinking a Pentax or such 3x9x40. Then I got to wondering about a simple red dot sight with multiple size dots. My shots would probably be no more than 100yds. Do these things work ok? Any particular brand? Or should I go with a scope?
Thanks.