This method is used for resampling with use of Rational Function Interpolation. This is a method to estimate data in the form of more complex Rational Function as follow;
Select data you want to apply this method in Analysis Window and click the icon of By Rational Function Interpolation. This will display a dialogue box for sampling setting as shown in the below. Input sampling values as you want and click Apply button. Then, you can get data resampled from sampling values you set. Since interval available to resampling is presented in this dialogue box, you can conduct resampling within this interval.