The search is focusing on Auchtermuchty Woods, the scene of a rave rumoured to have taken place around the time Allan went missing in November 2013.
Allan was last seen leaving Styx nightclub in Glenrothes on CCTV but his family believe he may have travelled to the remote site in north-east Fife afterwards.
Volunteers spent the day assisting the K9 search team in looking for clues in the wooded area between Auchtermuchty and Newburgh.
Allan’s uncle David Bryant helped co-ordinate the effort.
He said: “It’s something any family would want the closure to find out what happened.
“It’s a nightmare the pressure is phenomenal on the family.”
“The support is absolutely phenomenal, it’s what keeps the family going.”
VIDEO: Specialist dog team scours ‘rave’ scene in search for missing Allan Bryant