How do I add a dependency to Buildout?

I'm quite new to Buildout, but I just got my first Django application building in it thanks to the nice tutorial here. I'm used to using Maven, so how do I "add a dependency" so Buildout will download it and include it in the build? Here's my buildout.cfg file:

[buildout]
parts = python d开发者_StackOverflow中文版jango
develop = .
eggs = my-project
versions = versions

[versions]
django = 1.3

[python]
recipe = zc.recipe.egg
interpreter = python
eggs = ${buildout:eggs}

[django]
recipe = djangorecipe
project = my-project
projectegg = my-project
settings = settings
test = my-project
eggs = ${buildout:eggs} 

What do I need to change here to add a dependency to south, version 0.7.3 (or the latest)?

Add the name of the required dependency to setup.py's install_requires array:

setup(
    ...
    install_requires = ['setuptools', 'south'],
    ...
)