21-year-old, Louis, who once worked at the Doncaster Rovers club as a hospitality waiter, has been issued with the number 28 shirt for the 2013/14 season.
He has signed as a non-contract player in aid of Bluebell Wood Children's Hospice in Sheffield.
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The US president enjoyed rousing support for his political agenda as a formerly hostile audience cheered his plans in office to the rafters.
The former leader said the party needed to learn lessons after his successor Paul Nuttall failed to unseat Labour in a hard-fought campaign.
Toddler Harry Studley was left blind in one eye after Jordan Walters, 25, shot him in the head with an air rifle last year.