Sometimes, the distance window constraint used in RMCProfile fitting will cause some spikes in the tail region of some partial PDFs. In this case, the tail constraint could be applied to suppress those unphysical spikes. To do this, one can refer to the following tutorial video, which uses OriginLab for extracting parameters of a Boltzmann function to be used in RMCProfile settings. To use those parameters, one can refer to the manual.
N.B. The selection of parameters is a bit arbitrary and the critical principle is not to change the integrated area under the peak in the region bounded by the lower and upper limit in r-space to be used for the tail constraint.