Manager Jack Pearce and coach Robbie Blake swooped for striker Diedrick-Roberts after Bognor forward Jordy Mongoy alerted them to his availability.
Rocks general manager Simon Cook explains: "Kayne was introduced to the club by Jordan Mongoy, who played with him in Sweden’s second tier for IK Gauthiod.
"He is a forward who began with Fulham’s youth system before being snapped by United where he played in both their U18s and the UEFA Youth League sides alongside striking partner Marcus Rashford. After a spell out of football he made a return at Lewes where he played last season before moving to Sweden.
"Kayne has attended the last couple of games at Nyewood Lane whilst waiting for his international clearance from the Swedish FA and expressed his delight at the superb playing surface. He is looking forward to joining up again with Jordy in the near future."
Rocks fans will have to be patient to see Diedrick-Roberts in action with non-elite football on pause for a month as a result of the last Covid lockdown restrictions.