With this feature...
Do this...
use resistivity curve
Select the curve on which to base saturation calculations.
shale resistivity
Type the shale resistivity.
float shale 
auto shale
Select one of the following:
float shale to manually redraw portions of the shale resistivity
curve.
auto shale to automatically redraw the entire shale resistivity
curve.
water resistivity
Type the water resistivity for this zone.
saturation estimation method
Select the estimation method.
a m n factor
Type the factors.