The 24-year-old, who swims for City of Glasgow, came sixth in the nail-biting race last night which was won by French star Yannick Agnel in one minute, 43.14 seconds.
But Robbie, who studies engineering at Strathclyde University, remained cheerful and vowed to look to the future.
He said: "If I can keep going the way I'm going, who knows? In four years time I might get a medal.
He said he gave a "solid performance", adding: "I couldn't ask for much more. It's a PB (personal best) for me.
"I can't believe it just went by so fast but it was a good race for me. It was absolutely fantastic. The home support here is just brilliant."
Head coach at City of Glasgow Swim Team, Andrena Hammond, said the whole club was proud of his achievement.
She said: "I think that it was encouraging that he was taking about competing in four years time. He's obviously thinking ahead already.
"It is a very hard event for him but he powered through it. And he did better than he did last time at the Olympics.
"He's still young for a swimmer, he's continually getting better."
She said the Olympics were not the only competition on Robbie's mind. The top swimmer is also looking ahead to Glasgow 2014 where he is hoping to again scoop the gold medal for Men's 200m Freestyle which he won in Delhi in 2010.
She added: "We all can't wait for the Commonwealth Games to come to this city and Robbie wants to retain his title."
Robbie, orginally from Aberdeen, looked confident as he walked out to the pool in the aquatic centre, cheered on by the crowds who were waving Union flags.
Robbie launched into a strong swim, gliding through the water, before falling behind the stronger athletes. He secured a time of one minute, 46.53 seconds.
South Korea's Park Taehwan and China's Sun Yang shared the silver, behind Agnel.
Mairi Clark, chairwoman of the City of Glasgow Swim Club, said Robbie's Olympic turn was "amazing" for the organisation.
She said: "It is really exciting for the club, for him and for our members.
"It has been a lot of hard work for him, the dedication that these swimmers put in is incredible. It's inspiring for our swimmers to have that calibre of athlete around them."
Mairi, who called Robbie "quiet and genuine", added: "He always says Glasgow is his second home and he's excited for the Commonwealth Games to be held here."
Other Scots swimmers have high hopes for medals.
Both Hannah Miley and Caitlin McClatchey are through to their finals in 200m medley and 200m freestyle.