De Ridder joins RKC
The former Ajax, Celta Vigo and Wigan Athletic attacker spent last season at Heerenveen, but has been troubled by a neck injury and not featured for any club since.
However, the 29-year-old Dutchman is now set for a return to the Eredivisie, having previously impressed during a trial at RKC.
"We are very pleased with the arrival of Daniel," said technical manager Janus van Gelder. "He's at his best on the flanks and we currently need cover in that position as we have injury problems.
"What really appeals to us all is the drive that Daniel has.
"He wants to be in Holland to show what he can do.
"We offer him a stage here and in this way we hope to work together in the coming months."
RKC are one place above the Eredivisie relegation play-off zone, but have not suffered defeat in six league matches.