Cummings joined Forest in the Championship in England from Hibernian in Scotland in the summer transfer window.
McKay has also made the switch to the Reds in the summer, making the switch from Scottish giants Rangers.
Scotland international striker Cummings, 22, has praised his Forest teammate and 22-year-old winger McKay.
“I would have him in every single squad,” Cummings told The Glasgow Evening Times about McKay about playing for Scotland.
“He is one of the best players I have played with and I’m sure he will be a big player for Scotland in the future.”
McKay is a very talented footballer, and playing in England and working with manager Mark Warburton is only going to make him better.
The winger has scored four goals and provided seven assists in 13 Championship starts for Forest so far this season.
Cummings’s comments underline the mistake Rangers made in selling McKay in the summer transfer window.
The Ibrox outfit should have kept hold of the winger, as he would have been a brilliant player for the Gers in the coming years.
Rangers’ loss was Forest's gain.