OFCI items appear in schedules, keynotes and spec sections. The owner pays for the product. The contractor prices receiving, storage, handling and installation.
Example: an equipment schedule marks kitchen appliances as OFCI. The contractor prices labor to set and connect them but not the appliances.
Price the labor and leave out the material. Ask who unloads, who stores and who is responsible for damage or missing parts. Check what the spec says about warranty on OFCI items. State in your proposal that the price covers installation only.