Create a new indicator, copy the rsi source code into it and change it into an average. Why not?
For example, the following ma(rsi 1,10); Is the daily average of rsi 1,
LC := REF (closing price,1);
RSI 1:=SMA(MAX(CLOSE-LC,0),7, 1)/SMA(ABS(CLOSE-LC),7, 1)* 100;
RSI2:=SMA(MAX(CLOSE-LC,0), 14, 1)/SMA(ABS(CLOSE-LC), 14, 1)* 100;
Ma (RSI 1,10);
Ma (RSI2,10);