The Genealogical Society of South Africa
The Genealogical Society of Utah (GSU), an organ of the Latter Day Saints (LDS), has published a collection of black and white photographs of a number of South African church registers here: Historical Record Collections - Africa
One of these collections is listed as South Africa, Dutch Reformed Church Registers, 1660-1970. In fact these appear to be church registers of the Nederduits Gereformeerde Kerk (NGK) from that denomination's archive, The NG Kerkargief, Noordwal-Wes, Stellenbosch, South Africa.
There is an index in the process of being compiled, also called:
Items found in that index link to the images of the registers pages, but there is no information as to whether these are all completely indexed or not.