Scott told Radio Sheffield that all parties couldn't come together in time to agree a deal for Harley to return.
"It wasn't just an issue with Notts County, it was with everyone having time to get a deal done quickly. Jon had done well with us so maybe it's something we can look to do in the summer, but we had got other names lined up and if Scott Griffiths does well then his name is on the cards too for a permanent deal," said Scott.
Full back Rob Kozluk had also been training with the club but signed for Bradford on Wednesday, as the boss continued: "Rob was an option but I had other positions to look at like the left hand side. Griff and Sam Wood were my priorities.
"I'm happy with the squad and with Cressy coming back we've got defensive options now plus we can throw Richard Naylor in there. Rob was excellent while he was training with us but he got a contract with Bradford until the end of the season."
Of winger Jack Compton, a name first linked to the Millers last week by MillersMAD, Scotty said: "Jack did well at Bradford and he's a name we've spoken about. He has ability and can cross a ball and we will keep a close eye on him."
Compton has returned to Falkirk after his loan stint at Bradford came to an end.