Doncaster have made forward Dany N'Guessan their sixth summer signing.
Tottenham have confirmed that Romanian defender Vlad Chiriches has completed a move to Napoli.
The 36-year-old left Bolton earlier this summer after 10 seasons at the Reebok and has dropped down into League One to join up with Simon Grayson's side.
Davies, handed the number nine shirt at Deepdale, became England's oldest debutant for 60 years when he lined up against Montenegro in 2010.
He departed Bolton in May having made over 350 appearances, scoring 84 goals.
The former Southampton forward scored six times in 38 games for the Trotters last season and is available to make his North End bow against Liverpool on Saturday.