Your question's title suggests the market prices are mean reverting. I strongly suggest verifying that assumption via one of the usual tests, such as the Augmented Dickey-Fuller test (implemented in the tseries package of R by the adf.test function, and in other R packages, too).
If the market is truly mean reverting, a possible strategy is
- Detrend the data.
- Monitor the market for an extreme high or extreme low, based on its historical range.
- Buy or sell-short the market at those extremes.
- Cover at a logical point: at the mean or at the half-way point, for example.
Detrending is useful to eliminate the long-term trend (in stocks) or eliminate the effects of carry (in futures). "Extreme highs" and "extreme lows" must really be extreme: I look for prices in the upper 90 to 95th percentile or lower 10th to 5th percentile, based on a few years of history.
Buying or selling-short at the extremes is fine ... unless the market decides to exceed its historical limits, in which case you'll experience drawdown, potentially large. I use a momentum filter and that helps but it's not perfect.
My experience is mostly in trading mean-reverting spreads. Your mileage may vary.
(PS - I found no connection between the RSI indicator and mean reversion. I don't use it.)