The South Africa-born Proudfoot played for both Edinburgh Reivers and Glasgow and earned four Scotland caps after qualifying through a Dumfries grandparent.
The 44-year-old has previously worked with Coetzee at Western Province, the Stormers and Japanese club Kobe Steelers.
Proudfoot is to be tasked with overseeing scrummaging, the breakdown and all aspects related to contact areas, while fellow assistant Johan van Graan will look after attack and lineout play. Part of Proudfoot’s responsibilities will be the same as those that were undertaken by Richie Gray, the former Gala captain who was breakdown coach under previous South Africa coach Heyneke Meyer. Gray went on to assist Scotland in that department during the recent Six Nations before returning to work with the South Africa Sevens team ahead of the Rio Olympics.
Proudfoot played in all three internationals for Scotland on the 1998 tour to Fiji and Australia while he was in the Edinburgh Reivers squad before injury the following year appeared to have cut short the prop’s Scottish career.
However, he came out of semi-retirement to play for the Leopards in the Currie Cup and Blue Bulls in Super Rugby.
His former Scotland forwards coach Hugh Campbell convinced Proudfoot to return for a season with Glasgow in 2003-04 and he earned one more Test cap in a Rugby World Cup warm-up against Ireland at Murrayfield.
Proudfoot said: “The Springboks are at the beginning of a new era under the coaching guidance of Allister and I am very excited and very grateful for this opportunity. It is a huge honour to be part of the Springbok coaching staff and I am looking forward to this challenge.
“I am very grateful to the Kobe Steelers for allowing me to join the Springboks. I enjoyed my time with them immensely and I want to wish them all of the best for the future.”
Coetzee added: “I know Matt very well from our coaching stints together in Cape Town and Japan and have a lot of respect for his ability to build a powerful pack and his rugby philosophy.
“I am confident that he will add a lot of value to our management staff and the coaches are looking forward to working with him.” The new Springbok regime’s first challenge is the three-Test home series against Ireland next month.
Proudfoot’s coaching career started with the NWU-Pukke club before acting as scrum consultant for the Stormers in Super Rugby. He went on to become Coetzee’s assistant coach there and at Western Province, where he was responsible for the forwards.
Coetzee was Jake White’s assistant when South Africa won the World Cup in 2007 and has now been charged with bringing through a new generation.
South Africa recovered from a shock defeat by Japan in their World Cup pool last year to reach the semi-finals. They pushed eventual champions New Zealand close before losing a tight encounter.
That led to Meyer’s departure and Springbok stalwarts such as Victor Matfield, Jean de Villiers and Fourie du Preez also called time on their Test careers.