I decide to finally try out this plugin with Sketchup v8 on my Mac. I used the Preferences/Extentions/Install Extension... method after renaming the ZIP file extension to RBZ. The files were installed as stated in a previous post here called "The most common reason that plugins don't work..." with a slight variation that doesn't allow the plugin to work.

The version that I downloaded was for the Mac and was called "draw_angle_dim_Mac". The above extensions installer within Sketchup v8 installed the plugin correctly but one folder level too deep. The installation folder was named the same as the ZIP file "draw_angle_dim_Mac".

You have to move the Ruby script "draw_angle_dim.rb" and the folder "draw_angle_dim" up one level for the plugin to work in Sketchup. Get rid of the folder "draw_angle_dim_Mac".