Makaay played with Fer at Feyenoord and has kept a close eye on his dutch team-mate since he joined the Swans.
Fer spent two and a half seasons playing alongside Makaay at Feyenoord and the former Bayern Munich striker has watched Fer closely since he joined the Swans permanently this summer.
Swansea City's Leroy Fer scores their first goal
The 41-year-old told Swansea's official site: "Myself and Leroy have always kept in touch since he left Feyenoord.
"He's not only a former team-mate but also a good friend.
"I'm really glad he's doing so well at Swansea. I can remember it was at the end of my career that Leroy was my team-mate. He was 19 and was as big as he is now.
"I saw he had the quality to be a good player - he has power, is a box-to-box midfielder and can score goals."
Swansea City's Jay Fulton in action with Liverpool's Dejan Lovren
Fer has been among the Swans' top performers and is currently their leading goal scorer with four Premier League goals so far this season.
Mackaay added: "Swansea haven't had the best of starts, but he's scored four goals in seven games - that's not bad for a midfielder.
"He's fitted in well there and is well suited to the Premier League. He's only 26 and I think there's more to come from him."
Makaay had an impressive playing career and can boast a European Golden Boot, two Bundesliga and German Cup titles along with a La Liga winners’ medal and Dutch Cup trophy among his achievements.
The former centre-forward is now part of Feyenoord's youth coaching system after being promoted from assistant coach.
Fer made his first start for Feyenoord at 17 after coming up through their academy.
The midfielder joined Swansea permanently this summer from QPR after a brief loan stint to the club at the end of last season.
Swansea City manager Bob Bradley poses after the press conference
The Swans currently sit in 17th place after sacking former manager Francesco Guidolin and hiring American Bob Bradley to try and turn their season around.
Swansea will return to Premier League action with a visit to the Emirates to face third-placed Arsenal this Saturday.