My rabbit like to sit in the rain will she be OK .

Is it a warm rain or a cold one? What is the outside temperature? Does she have shelter to go into?

It's not very good for a bunny to get wet and stay wet, especially if the weather is cold.

What is her shelter like? Is her bedding area perhaps dirty? Have you cleaned out her bedding lately? Bunnies are actually very clean animals and they don't like to sleep in their own mess. If the bedding area is messy she may sit outside rather then go into the messy area.