I use Schedule C. I don't have a company so just enter under my name. I have eBay sales - I enter the 1099k amount as income. Enter shipping, fees, and other non-inventory expenses - if there aren't relevant categories, enter as other. you can't show a loss, but you can net 0 - the difference between revenue and the expenses is your cost of goods sold. Your situation may need tweaking, but hopefully this helps.
