Current register format is in 2's complement. The LSB size is 1.5625uV/RSENSE, where RSENSE is the sense resistor.
For example, for MAX17201evkit, the default sense resistor is 0.01ohm. Thus the LSB size would be 1.5625uV/(10mohm) = 0.15625mA
The table below is a capture from the evkit GUI as an example.
To convert from 0xF163 to the corresponding current, the calculation is as follow:
Since the most significant bit is high, this is a negative current.
To convert from the binary value to decimal,
0xFFFF-0xF163+1=0x0E9D=3741 in magnitude.
current = -3741*0.15625mA=-584.53125mA, which matches the value posted in the GUI above.