Seismic noise RMS amplitude

Does anyone know any function to compute the RMS amplitude from the PSD obtained by ppsd or from the raw data? I want the ambient noise RMS values at a certain frequency band.

I believe there are some equations to estimate RMS from PSD, I think there is something on it in the New Manual of Observatory Practice.
And computing RMS from the time series data should be trivial using numpy, I believe? If you want a certain frequency band you could filter before doing the RMS calculation.

I appreciate your advice. I found how to do it in the New Manual of Observatory Practice as you suggested.