At the end of a lot of the actual wmv files used to create the Realtracks there are often a variety of samples.
Cymbal crashed and other drum hits are often recorded separately one at a time, these can be used as 'samples' to create what you need to match the existing sound. You need to copy the drum or cymbal you want and paste it where you want, or use a VST sample player to do it. It's really not that hard.

Some realtracks have unique things hidden in them also, but the drums are usually pretty easy.

Make your sound your own!
.. I do not work here, but the benefits are still awesome