Depends on your appointment, the country you are going, and if
the country you go have pre-agreed arrangements.
THree general modes of travelling overseas representing, SAF.
1) Travel by nominal roll,
Receiving country will receive a copy of your photo, and id
details. Just present yourself at their airport, they will just
stamp your in/out endorsment in SAF's copy of the list.
2) Travel by Passport
Just like any other travel. Usually for countries where SAF do not
have regular training with OR that country's law do not provide for
such arrangements.
Some service personnel in the frame who will travel by nominal roll
will travel using passports, this is in case there is emergency
they will need to leave without the others.
3) Diplomatic Passage
SAF will go thru Mindef and Foreign Affairs who will request
admission of servicepersonel into that country. Usually for last
minute incidents (eg, Tsunami).