Although not charged on the field, Schoeman was issued an off-field red card by the competition's citing commissioner for alleged foul play during the Bulls' 28-10 win at Loftus Versfeld in Pretoria.
The Rebels said their captain Tom English had alerted the on-field referee of the alleged bite when Schoeman and Hardwick clashed in the 58th minute.
"Melbourne Rebels club captain Tom English at the time of incident appealed to the referee and gestured towards the evidence on Hardwick’s stomach, however the initial penalty call against Hardwick was upheld," a Rebels spokesman said in a statement emailed to Reuters.
A hearing has been scheduled for 9 a.m. local time in South Africa (0700 GMT) on Monday, governing body SANZAAR said in a statement.
If found guilty, Schoeman could face a long stint on the sidelines.
In 2016, Argentina loose forward Leonardo Senatore was suspended for 10 weeks after being found guilty of biting the arm of a Sharks opponent when playing for the Jaguares in a Super Rugby match.
The Rebels (4-4) travel to Cape Town to play the Stormers (3-6) this weekend, with the Bulls (4-4) hosting New Zealand side Otago Highlanders (5-2).
(Reporting by Ian Ransom; Editing by Peter Rutherford/Amlan Chakraborty)
