Configure the simulink spectrum analyzer with custom Span (Hz)

I am using the Spectrum Analyzer in Simulink. I need to see the signals in the 100kHz range with about 20kHz band in more detail.

1) if I leave more-less the default setting of the Spectrum Analyzer with Full frequency span and my sampling rate is 96MHz (increasing) then I do not see details of the frequency spectrum well enough and RBW resolution bandwidth increases with sampling frequency (12MHz->24MHz->96MHz) to 93.75kHz.

How to set the Spectrum Analyzer to see the spectrum with fine RBW (~1Hz)?

2) if I costumize the Span (Hz) then the Spectrum Analyzer requires too many samples (~7M). Can I get lower the number of samples?

3) If I use instead of RBW setting the Window length (4096, etc...) then I see the following error:

How should avoid (fix) "Output argument "PSD"" error?

How to set the Spectrum Analyzer correctly to see the "fine" Spectrum with RBW = 1Hz?

Can it be set up the Spectrum Analyzer with reasonable "normal" number of samples since I would like to have simulation responsivness?