QTR-Quadtone RIP

In QTR help file under "Ink Density Calibration" I don't understand 
how to do the following :

"The darkest ink limit will be called 100. Now match the density of 
the limit for the next lighter ink with the matching density of a 
percentage of darkest ink".

Also, using a scanner and the eyedropper is ok but how to use the Eye1 
instead ?

Many thanks for your answers

Michel