This is from the QSO Party rules link above:
Exchange: Ontario stations send signal report and their county abbreviation as per the Ontario county multiplier list. Ontario stations must log received signal report and county, province, state, or DXCC country abbreviation (the abbreviation “DX” is also acceptable.
Non-Ontario stations send signal report and province, state, or DXCC country or abbreviation. Non-Ontario stations must log received signal report and county abbreviation as per the Ontario County list.
Scoring: Ontario stations work everyone. Non-Ontario stations work Ontario stations only. Mobile/Rover stations may be worked again when they change multiplier areas.
Score 1 QSO point for each station worked on phone per band. Score 2 QSO points for each station worked on CW per band. You may work a station TWICE per band: once on phone and once on CW.
Score 10 QSO points for each contact made with CCO club station VA3CCO, ODXA club station VE3ODX, and RAC Ontario club station VA3RAC.
All fixed stations claim 1 multiplier point for each Ontario county worked on each band. see Ontario county multiplier list.
Ontario fixed stations also claim 1 multiplier point for each Canadian province/territory, U.S. state and DXCC country worked on each band.
Rover/Mobile stations claim the sum of multipliers worked from each different location.
Total Score = Total QSO points x total multiplier points.