[Radiant] how to install an extension?

[Mark D. Anderson]

apparently there is more to installing an extension than simply un-tar-ing
in the vendor/extensions directory and running "rake db:migrate:extensions"
i put the "external_rss" and "gallery" extensions in the vendor/extensions directory,
ran that rake command, and also ran "rake radiant:extensions:external_rss:update:public".
No errors were shown.

However, the admin didn't show them as extensions.
so then I restarted the server (does every extension install require a full restart?).
then the thing wouldn't run at all.
my apache error log has:

[Fri Oct 05 00:27:16 2007] [notice] mod_fcgid: server /group/apedf.org/public_html/dispatch.fcgi(29161) started
/usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/vendor/rails/activerecord/lib/../../activesupport/lib/active_support/dependencies.rb:266:in `load_missing_constant': uninitialized constant ExternalRssExtension (NameError)
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/vendor/rails/activerecord/lib/../../activesupport/lib/active_support/dependencies.rb:452:in `const_missing'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/vendor/rails/activerecord/lib/../../activesupport/lib/active_support/dependencies.rb:464:in `const_missing'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/vendor/rails/activerecord/lib/../../activesupport/lib/active_support/inflector.rb:250:in `constantize'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/vendor/rails/activerecord/lib/../../activesupport/lib/active_support/core_ext/string/inflections.rb:148:in `constantize'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/lib/radiant/extension_loader.rb:70:in `activate_extensions'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/lib/radiant/extension_loader.rb:68:in `select'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/lib/radiant/extension_loader.rb:68:in `activate_extensions'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/lib/radiant/extension_loader.rb:42:in `run'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/lib/radiant/initializer.rb:43:in `initialize_extensions'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/lib/radiant/initializer.rb:36:in `after_initialize'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/vendor/rails/railties/lib/initializer.rb:114:in `process'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/vendor/rails/railties/lib/initializer.rb:43:in `send'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/vendor/rails/railties/lib/initializer.rb:43:in `run'
        from /usr/lib/ruby/gems/1.8/gems/radiant-0.6.2/lib/radiant/initializer.rb:32:in `run'
        from /group/apedf.org/public_html/../config/environment.rb:15
        from /group/apedf.org/public_html/dispatch.fcgi:21:in `require'
        from /group/apedf.org/public_html/dispatch.fcgi:21
[Fri Oct 05 00:27:19 2007] [notice] mod_fcgid: process /group/apedf.org/public_html/dispatch.fcgi(29161) exit(communication error), terminated by calling exit(), return code: 1