Only the captain should his feet lightly on the rudder pedals at all times
Why? His feet should be on the floor - never should the captain be "following through" on any controls when he is PNF. There is simply no need for it. If he does not trust the F/O to fly then as captain he has the responsibility to report this and arrange for more training for the first officer. If the captain cannot take over control within a fraction of a second if something goes badly wrong then he should not have the job as captain.
Of course some captains are very nervous regardless how good the F/O at his job and these captains are known to hover nervously over the controls when the other pilot is flying. It is then the captain that needs further training to improve his personal confidence.