There's no way you can decide to do a reality check in a dream where you are totally non-lucid. The trick to RC's is that you have to make them part of your life, doing them rather often while awake. Chances are that your dream just happens to perform one and thereby trigger lucidity. They are also very nice for when you have doubts whether you are dreaming or not, and to test if an awakening is true or false.
So, if you want to increase the chances of you doing a RC in a dream, you have to do them in real life as well.