Hi,
The address will be display automatically during the registration if the user do not have a Joomla account (and so, no HikaShop account either).
By editing the custom field in the HikaShop backend, you can tweak where the field will be displayed, in the HikaShop parts but also in some HikaMarket parts (even if HikaMarket will use some HikaShop settings regarding the registration in order to mimic the HikaShop registration).
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.