Yes, RSI is one of the key flags in our ChartSignals package. You can screen for RSI Overbought and RSI Oversold stocks (using the 14-day RSI).
RSI uses all the price changes that occur over a given period in order to derive the average price change. Essential to the calculation is creating the ratio U/D calculated by dividing the moving average of the total price points gained on 'up' days (U) by the moving average of the total price points lost on 'down' days (D). This ratio is then 'indexed' to create a number that moves between zero and 100 as follows: RSI = 100 - ( 100 / (1 + U/D) ). Its creator, Wilder believed that readings above 70 signalled an overbought stock whereas readings under 30 signalled an oversold one. We discuss RSI and its interpretation in much more detail here.