So-called normal RSI uses EMA smoothing with period = 2*Length-1 (or Wilder's smoothing with period=Length).
I've developed RSI indicator with my algorithm of calculation.
Now you can use any values for length and any kinds of smoothing.
This version can use up to 2 Moving Averages applied to that RSI in order to filter out some false signals (when RSI is used in combination with levels crosses). In this version you can use smoothed values of the RSI for signals. To set any of the averages off, set the average period to less than or equal to 0.
This is an MQL5 version of the Expert Advisor described in the article "How to reduce trader's risks" (https://www.mql5.com/en/articles/4233).