Technically most signings are identified by the heads of scouting but the credit is given to the DoF.
But in this case, we can say that Potter has been influential in signing the player because the head of recruitment he brought over from Brighton to work within your club structure has gone and done the deal. And I presume with Winstanley's track record as a recruitment head, he would've had a dossier on the player.
I would bet a lot of money that Potter's involvement in this signing was this:
"Potter, would you be happy with this guy"?
"Yeah, sure. I trust you.".
It that makes it a "Potter" signing then fair enough.