C.L.
Here is a link to a good article on crate/potty training....
http://www.inch.com/~dogs/cratetraining.html
I noted in the article it says."A Note About Crating Puppies
Puppies under 4 months of age have little bladder or sphincter control. Puppies under 3 months have even less. Very young puppies under 9 weeks should not be crated, as they need to eliminate very frequently (usually 8-12 times or more daily)." I don't recommend rubbing them in it, as it just makes a bigger mess for you to clean up, and they have no clue why you are doing it. Sorry girl but 4 months is about the magic number. Puppies are a lot of work, including potty trips outside. If you have kids in the same yard, training them to one spot is a good idea. My parents used pea gravel where they wanted their dog to go and trained her to that spot. Made very easy cleanup and we didn't have to worry about stepping in poo in the yard.
Good luck!
C. Livingston