AAM resistor Value - MP2313

I would like to ask some information regarding the AAM resistor value. Performed the measurement for different load (100,300,500)and calculated efficiency for 3 different values of AAM resistor.
Specification in test measurement:

Vin: 13.5V, Vout:3,3V, L-2,2uH.

1.68K
2.40.2K
3.37.4K ( this value is calculated as per the specification input - Figure 7, AAM value -0.225)

Results

  1. 68K efficiency is high and switching frequency not within the specification for light load current.
    Ex:efficiency =86%, fs = 1.0936 load current = 100mA, Vin=13,5V

2.40,2K, efficiency is reduced and switching frequency is within the specification for light load current
Ex.efficieny = 73%,fs = 1.998, load current = 100mA, Vin=13,5V

3.37.4K,efficieny is reduced further and switching frequency is within the specification for light load current
Ex. efficiency= 69%, fs=1.953, load current =100mA, Vin=13,5V

Questions

  1. Which resistor value is recommended to choose from the above results?
  2. which factors is important in terms of choosing the resistor value is it switching frequency or efficiency for light loads?
  3. when the resistor value is calculated as per the specification, efficiency is low? why? based on how the value needs to be calculated.

I would like to know the feedback for the above question? When I created the ticket it was mentioned that I will get the reply within 1 business day