Close!
the <consumerKey> in the docs means that whole string should be replaced by your consumer key, including the < and >.
If your consumer key was 98237yhufhliuy9428huwn, then the relevant part of the plist would be:
<array>
<dict>
<key>CFBundleURLSchemes</key>
<array>
<string>twitterkit-98237yhufhliuy9428huwn</string>
</array>
</dict>
</array>
FWIW, what you’re doing here is specifying URL schemes your app can open. When a user signs in via the Twitter app, the Twitter app will try to open a url like this: twitterkit-98237yhufhliuy9428huwn://login_callback. Since you’ve told iOS that this is a URL scheme you want to handle, iOS will open your app and pass in this URL.
If you leave off the twitterkit part, when the twitter app tries to open that url, no app installed can handle it.
Happy hacking!