Riis met a cross from Brad Potts flush on the volley and found the net to earn a point.
It was the second time Riis had equalised in the game, the Robins having taken the lead first through Chris Martin and then Antonie Semenyo.
Here are the player ratings from the Championship clash, with Riis pick of the bunch.
9. Greg Cunningham 5
Couldn’t get going in the left wing-back role, with little joy pushing forward. Cunningham was replaced at half-time. Photo: Camerasport
10. Cameron Archer 7
A pleasing home debut for the loanee, his shot leading to the first equaliser. In the second half he looked for and found space well. Photo: Mick Walker/Camerasport
11. Emil Riis 8
His two goals earned PNE a point, the second in stoppage-time a volley of the highest order. His first was a good poacher’s goal. Photo: Mick Walker/Camerasport
12. Josh Earl 6
A half-time sub, his introduction was designed to get PNE higher up the pitch. Did okay but needs to be prepared to take players on. Photo: Camerasport