A website address, domain name or uniform resource locater (URL) is the primary information search engines use when determining which country your website is from when returning your company as a potential answer to a search enquiry.
When this is unclear that is to say your site uses a premium domain or a dot com how does the search engine know which country you represent. There are a few other things you can do.
The head section is all the information placed between the opening and closing head tag. Here you can place language information in the main html declaration tag section. You should use en-za which simply means South African english.
Additionally Google particularly enjoys using the tag hreflang. Follow this link for more detail.
You could also consider using the open graph tag og:country-name
The safest way to ensure that a search engine knows your websites country of origin is to consider (where available) using their respective webmaster tools.