Hi,
I think that the best solution will be to create a custom field through "Hikashop->Display->Custom Fields" and set the table to "Product" the type to "Text". Also, don't forget to publish it through your front-end and back-end.
Your custom field will then appear through the "specification" tab of your product page, but if you really want it to show under your product name, you can do it by editing the code of your show_default file of your product view of your front-end template through "Hikashop->Display->Views".
Note that custom field are only available through the business version of Hikashop.