Mladen Petric doubled the lead four minutes before the break, heading home from a corner which was almost cleared off the line.
The Fulham debutant scored his second in the 53rd minute, lashing the ball from 30 yards with a deflection ensuring Ruddy had no chance.
Kacaniklic added Fulham's fourth on 66 minutes, with a wonderfully-crafted goal. Petric flicked Moussa Dembele's pass through to the young Swede for his first Fulham goal.
Hugo Rodallega was brought down in the box on 85 after further poor Norwich defending with Steve Sidwell hammering in for 5-0.