Calculating the Resistor's Power Rating
The feedback voltage on this part is about 1.2V, so nominal power dissipation in the 976 ohm resistor is about 1.5mW.  (V^2/R) There's 3.3V-1.2V or 2.1V across the 1.54K resistor which will dissipate just under 3mW.  There's no value given for R3, but it will also dissipate negligable power if chosen correctly.  You can use the same technique to calculate the power at other output voltages with other resistor values.  Generally you can pick a feedback divider so that the power dissipation in the resistors is negligable.