LM5060: Isense and Voffset confusion

I am trying to determine the Rs resistor value for setting a specific current, however the datasheet is not very clear on the selection of the Rs resistor.  It lists an equation for Vdsth = Isense * (Rs - Voffset) but does not explain what Voffset is.  I understand that the Rdson of a specific mosfet and a max current determines the Vds develope across the mosfet drain to source.  Likewise, I understand the Rs being used to set a desired trip current as a function of a constant current of 16µA and the relationship between the Vdsth and this sense resistor.  But how and what determines Voffset to complete the equation?  The specific evaluation board shows a 9.09K resistance based on a linear graph.  The EVAL states a Rdson of 25mΩ and a desired Imax of 5A for the desire.  This yields a 0.145V Vds drop.  Likewise, if I calculate out the selected Rs of that EVAL of 9.09K, 9.09K*16µ = 0.145, which just happens to be equal to the Vds drop for the desired current and selected mosfet.  However, I don't see how Voffset plays into this.  Does anyone have a good explanation of this?  How should we actually select the Rs sense resistor for a desired trip current given the Rdson of a specific mosfet? Or, if Voffset just some dynamic element designed into the chip which developes another voltage to maintain the 16µA of current and we just use the the previous equations and neglect the Voffset given this seems to be a mistory.