Contact is not a requirement for a runner interference call. The ASA rule book flat out states that. Interference can be called if the runner's positioning or proximity to a fielder in the act of fielding a batted ball hinders her opportunity to make a play. In this case, the fielder 100% has the right of way.
Interference without contact requires a little more judgment from the umpire. Here are two examples of similar plays, one interference and one not.
1) Runner on first base. Ground ball to F4. The fielder is playing back behind the baseline and is stationary, stopped, waiting for the ball to come to her. The runner crosses in front of the fielder while advancing directly to the next base.
This would not be interference. The runners positioning did not impede the fielder's path or opportunity to field the ball.
2) Same situation...except...the fielder is charging in to field the ball. If the fielder has to "check up" or alter her path to the ball due to the runnner's positioning, then that can be interference. Contact is not necessary.
And don't forget that the rules also allow an interference call for verbal interference, which obviously requires no contact. Picture a pop fly where the runner screams, "Look out!", or, "Miss it!", as she passes the fielder. The runner can be called for interference, same as if she plowed into the fielder even though she never touched her.