Hi,
You can use "item custom field" if you want the information be in the product page (when the customer add the product in his cart).
You can use "order custom field" if you want the information be during the checkout.
These two kind of custom fields are provided by HikaShop Business.
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.