I'm not sure this is what you are asking, but I decided that it wasn't worth doing RSH after doing RTK.  I found that working on Chinese text was enough to get the  new meanings into my head.

The biggest problem when doing reviews is not multiple keywords for the same character, but the same keyword for different characters! It happens a lot if you do RTK+RSH, and it causes you to fail much more cards than you should, therefore wasting a lot of time and even stressing yourself out depending on your personality (that is, how you deal with 'failure'). Because of that, I would say it's better to use only one set, be it RTK or RSH, and then add subsequent characters based on that set. In my opinion, hanzi would be better to use as the main focus because, well, it's from where the kanji come from and there are quite a few great Chinese dictionaries to help, but the thing is that there's a lot more ready-made Heisig material for kanji, so it's up to the individual to choose.

Just to add something as to why you shouldn't worry too much about the keywords: as you may know, the idea behind them is not to teach the true meaning of the characters (and most of the time it's not even possible to "translate" one to a single English word without impairing its meaning), but to associate them with something you already know so that you recall them better; it's nothing more than a mnemonic device. Then, if you end up creating your own cards, which will be needed if you intend to use Heisig's method to learn more than 3000+ characters, you'll probably notice that there's a point where there's not a single word that can be used to express the subtleties of the character well — and, when there is, the keyword is already taken...

Although I believe the keywords are useful during the first stages of learning the language, I believe in the end the goal would be to discard all of them and simply have the characters being part of you below the level of words — that is, no more associating them laterally (from one language to the other) but vertically (from the idea/concept/feeling/reaction/sound to the character).