Because it is originated from a convolution of a Gaussian and an exponential, which decreases starting from the Gaussian's centroid, it is an asymmetric function. Therefore when the right skew is added to a Gaussian peak, it causes slight increase at the high energy side of the peak.
The fitted parameters for Right skew are the Right Skew Amplitude (relative to the Gaussian's amplitude), and the Right Skew Slope. The width of the right skew is not fitted, but assumed to be always equal to the width of the Gaussian. The picture shows a right skew with Slope=1 and relative Amplitude=0.25.

RSAmpl:
 Right Skew Amplitude relative to that of Gaussian (may vary from 0.0 to 0.75)
 
RSSlope:
 Right Skew Slope (0.3 – 2.0)
 
Ampl:
 Amplitude of Gaussian
 
Pos:
 Position of the Gaussian centroid
 
Width:
 Gaussian width (Width = FWHM/1.66),
