Different Price per size

-- HikaShop version -- : 3.5.1
-- Joomla version -- : 3.6.5
-- PHP version -- : 5.6
-- Browser(s) name and version -- : IE11

How can I create an item that has different prices per size?

So if I have a coffee that comes in small medium, and large, How would I create the pricing option with a drop down?

What if they wanted to add flavoring as well?