Hi Tsun! This is an important question. The best discussion of luck that I've heard/read is Greg Costikyan's "Uncertainty in Games".
Ro sham bo's most fascinating skill element lies in the fact that you begin the game with your hand in a fist (rock), so statistically, people tend to use rock on their first play more than anything. When humans are involved, patterns always emerge.
How does your game work? What are its themes?