Carl Smith Collection
The Carl Smith Collection ...
... is a very useful tool to help researcher identify basic data and sources of information on individuals, organizations, buildings, roads, land matters and important events relating to Hong Kong, Macau and China's coastal cities from the mid 19th century onward. Read more...
The collection can be searched online at: http://www.grs.gov.hk/PRO/srch/english/sys_carlsmith.jsp
However the cards themselves cannot be viewed online, as explained by Bernard at the PRO:
Thank you for your inquiry.
To my understand, because of the concern of the privacy of the person and their descendants, image of the cards are not accessible on-line. We will let researchers access to them on-site or provide images to users who sign an undertaking to declare the images are used for their private study and research.
If you are not able to visit the PRO to view the cards in person, the PRO can help you. You can contact them at firstname.lastname@example.org, saying you'd like to request cards from the Carl Smith Collection. They will send you the form to fill out. You fill it out and send it with a check and once the check clears they send you the copies of the cards.
Thanks to contributors MH and Annelise for providing the information above.