If you want to make it absolutely clear that your company will only regard itself bound by a conventional signature, you must stipulate in your contract of employment (or any other contract) that 'signed' refers to a hand-written signature, excluding any signature appended by 'electronic communication' as defined in the Electronic Communications and Transactions Act, no. 25 of 2002.

The simple answer is no. Documents that are going to be used for overseas purposes, be it for an individual or company, can only be signed before a notary public.

An Apostille certificate simply means that your document that originates in South Africa has been authenticated or legalised by The Legalisation Section at the Department of International relations and Cooperation (DIRCO), or the Registrar of the High Court of South Africa, thereby authenticating the origin of a public document.