Ruster joins Robins
The 21-year-old has impressed Robins boss Andy King during a trial spell at the club and has agreed to sign with The County Ground outfit until the end of the season.
However, The Robins needed Football League approval and international clearance from The FA, in order for Ruster to put pen to paper with the Wiltshire club.
"I am very happy to be here. The staff have been wonderful to me and the squad have made me feel welcome right from the start," Ruster told the club's official website.
"I have been training with Swindon for a few weeks now but now the transfer has been completed, hopefully I can compete for a place in the side.
"My preferred position is wide right and I am looking forward to the month's matches ahead."
Ruster was recommended to King by Leeds United boss Peter Reid after the wide man trained with the Premiership outfit during pre-season.
He previously had a spell in France with Cannes before trying his luck in English football this summer.
Meanwhile, defender Jerel Ifil has returned to Division One side Watford following a successful one-month loan spell at Swindon.
Hornets boss Ray Lewington was keen to bring the 21-year-old back to Vicarage Road despite impressing King with his displays for The Robins and he joins Leeds United teenager James Milner in ending his loan spell at Swindon.
Ifil remains a transfer target for Swindon but Lewington wants the defender to sign a new deal at Watford, with his current contract due to expire at the end of this season.
"I watched Jerel at Swindon on Wednesday against Luton Town and he did very well," Lewington told the club's official website.
"We want him here, because our squad is potentially fragile - at the back just as much as anywhere else in the side.
"We'd like him to sign a new contract and feel he's got a future here.
"We sent him on loan for him to get first team experience and he did well.
"We see his future here at Watford."