RMS from calculation from PSD using Welch's method I've used Welche's method on a vibration signal to get the averaged FFT which I want to used to calculate the PSD from which I can calculate the RMS.

Within the Welche method i've use Hann window with zero overlapping. The following post states, that using 
windowing couses distortion in the energy, which has effect on the RMS:
https://community.sw.siemens.com/s/article/window-correction-factors .

However not using windowing might lead to spectral leakege.

My question is, that what is the correct way of dealing with this problem? Shall I use uniform windowing, or shall I use correction factors on the FFT?
Also, you can use the PSD for estimation of the RMS, the easier way for estimation of the RMS is a direct calculation. 

In case, you still want to use the PSD for estimation of the RMS, you should normalize the values by the square of the average value of the window. For the Hann window, the normalization factor will be $\frac{1}{4}$.

update
The question is a duplicate from RMS calculation in frequency domain after windowing