You make the call

[scrounge]

Sounds like roughing may not enter into this, because with the muffed snap and a loose ball laying around, it's not reasonably certain that a kick will occur at all. So unless the contact is otherwise a personal foul (spearing, illegal helmet contact, etc) or you think the contact could have been avoided once it was apparent a kick was going to be made, sounds like nothing on that front.

Absent that, all I have is illegal kicking, because of the ball not being controlled by a teammate or fulfilling the requirements of a drop kick. Fed has a case play that pretty much covers this one:

9.7.1 SITUATION A:

On a field-goal attempt, holder A2 muffs the snap and is attempting to gain possession of the ball on the ground when A1 kicks it between the uprights over the crossbar.

RULING: An illegal kick by A1. If the penalty is declined, the result of the play is a touchback as the illegal kick cannot score a field goal. (2-24-7)