Output Current limit Related quarries

Hi...
I am designing a smps with 12V 3A rating using TOP256YN.
There is a external resistor pin for controlling the current. What I understand that the current is the mos-fet drain current. What I have done, I used different values and checked the secondary output about at what load (Wattage) the top-switch triggering it's overload protection. During this process different resistors values provided different results.

Can this resistor be used as controlling the output load ? (As the voltage is constant at output, it will act as over current protection or maximum current allowed from secondary may be).
If yes then how to calculate this resistor value depending on my desired output current?
Also what is current reduction factor KI ? it's says that using this I can use the device from 30% to 100% current limiting factor, the maximum current allowed is 2.76A at primary side, How can I calculate primary current depending on my output current?

Please Help.