It comes as hot-and-cold Canterbury prepare to lose forward Harry Hayes for a week over a tripping charge.
On club debut, former Penrith forward Riki landed in the sin bin for laying a high shot on Jonathan Sua during Friday night's 32-12 defeat of the Bulldogs.
The match review committee has since handed the New Zealander a grade-two careless high tackle charge that will rub him out of next week's clash with the Sydney Roosters.
If he unsuccessfully challenges the charge, Riki will miss the following clash against Manly as well.
Riki looks set to become the 13th Broncos player sidelined for round nine, with fellow forward Brendan Piakura going down with a knee injury against the Bulldogs.
Aublix Tawha, Reece Walsh, Ben Te Kura, Blake Mozer, Payne Haas, Ben Hunt, Dlouise Hoeter, Grant Anderson, Jesse Arthars, Corey Jensen and Billy Walters are sidelined as well.
The Broncos will at least regain Patrick Carrigan for next week's clash with the Sydney Roosters after the Queensland representative served his two-match ban for a high tackle.
Hayes went on report for tripping Broncos halfback Adam Reynolds during Friday's game at Suncorp Stadium and has received a grade-two charge.
The 23-year-old will miss next week's clash with North Queensland should he accept an early guilty plea.
