Hello Alessandro,
We created our indicators as they were described from their authors. All indicators are open source and you cans see the codes in GtiHub. Here is the RSI code: https://github.com/PopovMP/FSB_Pro_Indi … ore/RSI.cs
When you export an Expert Advisor from FSB Pro, it includes all the necessary indicators in the same file. The exported EAs use the same formulas as FSB Pro and show the same results.
MetaQutes uses different formulas for some of their indicators. Most of them match exactly ours, but some of them has slight difference.
Speaking about RSI, it matches completely the MetaTrader formula (Our expert shows one decimal digit more):

FSB Pro doesn't use the MetaTrader's integrated indicators and if there is a difference in the formulas, it doesn't deteriorate the quality of our experts.
However, if you do want to use the exact MT formulas for creating strategies, you can take a look at Expert Advisor Studio. EA Studio is specifically designed for MetaTrader's fans.
Here is an example with the Stichastics indicator. It also matches MT 100%

Most probably you have different parameters of the MT indicators you have on your chart. The FSB Pro indicators has more parameters shown and allow better customization. Some times it is not possible to set the MTs indicators to correspond to ours because you cannot set all params in MT.
You can very easily compare the FSB indicators with the MT's indicators by creating strategies with the default indicator parameters. We made them as near as possible to the MetaTrader's one. Very few differences exists, but as I said before, it doesn't matter and we don't care.