Hi, I'm going to South Africa and I'm taking some of my kit with me which includes my knife. Is there anything you have to do like register them etc to take them on the plane (in the luggage obviously)? Cheers
Pack it into your hold luggage, it is knife, not a weapon, you have nothing to worry about.
Make sure it is well packed and won't be the first thing that falls onto the table if your bag is picked out for inspection at customs, maybe stick it into a sealed jiffy bag, inside a sleeping bag or rolled up jumper type etc..
Edited to add:
I am presuming you are taking some type of 'bushcraft' type knife, or Mora or such. If you plan to travel with something that looks more 'weaponlike' in a plastic sheath attached to a military belt or pack then hope your plane doesn't have to make an unscheduled landing on the way down, that kind of thing could land you in a spot of bother.
FYI
The last time I was down there (Namibia) I took my Alan Wood Woodlore along with five Stainless Mora's to give to folk down there.