The phrase "a riser at" is correct and usable in written English.
It can be used in contexts related to construction, architecture, or design, typically referring to a vertical element or component in a structure.
Example: "The architect specified a riser at each level of the building to ensure proper access to the stairwell."
Alternatives: "a vertical element at" or "a step at".
The samisen and singers are placed on a riser at the back of the stage, and the hayashi sit before them on floor level thus, their other name, shitakata, meaning "the ones below".
An army of instrumentalists and choristers filled the stage, and four soloists clambered around the open space near the podium or sang from various perches (a riser at the back, a lower balcony to the right of the stage).
The timpanist, bestriding the top of an implied pyramid on a riser at the orchestra's rear, whacked out his barbaric yawp at the beginning of Rug gles's "Sun-Treader" with marvelously simulated abandon.
Mr. Navarre is the band's brain center, its loop-master and live mixer; when he played "Rose Rouge" with the performing version of St. Germain at Irving Plaza on Friday, standing on a riser at the back of the stage, the dancers in the crowd knew all the cues.
— There are times when the limitations of the printed word come into focus, like when there is a need to convey how it sounded when Robert Pattinson, who stars as the vampire heartthrob Edward Cullen in the forthcoming movie "Twilight," stepped onto a riser at the King of Prussia Mall outside Philadelphia on Thursday evening in front of more than 1,000 mostly teenage girls.
The talar neck approach may cause anterior ankle impingement or a stress riser at the neck of the talus that would necessitate hardware removal.
The cause of the new fracture was proposed to be related to a stress riser at the uninstrumented portion of the femur between the IM nail and the screws in the DHS side plate.
And he was an early riser at the best of times; 6.30 if you were lucky.
Since she was hardly an early riser at the best of times, Alan could only assume that she must have slept badly.
For a given Damkoeheler number, the presence of coarse particles is found to improve ozone conversions in a riser with polyethylene particles at a high gas velocity, and with glass beads at a low gas velocity.
Time series of pressure fluctuations were recorded at different measurement positions in a lab-scale riser at gas velocities of 3.0, 4.0, and 5.0 m/s under dilute and dense flow conditions, with solids mass fluxes ranging from 0 to 232 kg/m232
