Hi,
If you have variants, you do not have the possibility to sell the main product, only his variants.
So you have to create a variant for the "size 1".
It is currently not possible to chose the characteristics in a product listing ; but it is possible to select item custom fields (which are provided by HikaShop business).
The reason that the characteristics are not available in a product listing is the amount of data that HikaShop should have to process/load in a listing.
Using item custom field will allow you to select a size but you will have just one single product in the database.
So you couldn't have different price per size, or different stock.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.