The Dane is on a four-man shortlist for October's award, the winner being announced on Friday morning.
He is up against Fulham striker Aleksander Mitrovic, Bournemouth's Lloyd Kelly and Blackpool frontman Jerry Yates.
In nominating Riis, award sponsors Sky Bet said: "Growing in confidence with every game, Riis scored four of Preston’s goals in the month he signed a contract extension.
Luton Town boss says best team didn't win after Championship defeat to Preston North End
John Smith's PNE Fans' Panel verdict: Sunshine all the way
Longridge Cricket Club will play at Emirates Old Trafford in a bid to win the Lancashire Knockout Cup Final
PNE player ratings vs Luton Town as Ben Whiteman and Liam Lindsay steal the show in hard-fought win
Preston North End defender says previous defeat inspired them to victory over Luton Town this time around
"His sweetly struck winner against Coventry was bettered by a driven shot from an absurd angle against Luton."
Riis' goals in October came away to Queens Park Rangers, the winner against Coventry City and then he got both in the 2-0 win over Luton.
He signed a new contract in the week leading up to the Luton goal, extending it by 12 months to the summer of 2025.
Thanks for reading. If you value what we do and are able to support us, a digital subscription is just £1 month for the first two months. Try us today by clicking here