Customizing the buttons

In the gem source (lib/rich.rb) you can see the default buttons defined in @@editor[:toolbar]:

@@editor = {
  :height => 400,
  :stylesSet  =>  [],
  :extraPlugins => 'stylesheetparser,richfile,MediaEmbed',
  :removePlugins => 'scayt,menubutton,image,forms',
  :contentsCss => :default,
  :removeDialogTabs => 'link:advanced;link:target',
  :startupOutlineBlocks => true,
  :forcePasteAsPlainText => true,
  :format_tags => 'h3;p;pre',
  :toolbar => [['Format','Styles'],['Bold', 'Italic', '-','NumberedList', 'BulletedList', 'Blockquote', '-', 'richImage', 'richFile','MediaEmbed', '-', 'Link', 'Unlink'],['Source', 'ShowBlocks']],
  :language => I18n.default_locale,
  :richBrowserUrl => '/rich/files/',
  :uiColor => '#f4f4f4'
}

To make local modifications in a rails project, edit your rich.rb initializer (config/initializers/rich.rb), and add your modified list:

if Object.const_defined?("Rich")
  Rich.setup do |config|
  # ..snip..

  # default list  
  config.editor[:toolbar] = [['Format','Styles'],['Bold', 'Italic', '-','NumberedList', 'BulletedList', 'Blockquote', '-', 'richImage', 'richFile','MediaEmbed', '-', 'Link', 'Unlink'],['Source', 'ShowBlocks']]

  # modified list with text alignment (for example)
  config.editor[:toolbar] = [['Format','Styles'],['Bold', 'Italic', '-','NumberedList', 'BulletedList', 'Blockquote', '-', 'richImage', 'richFile','MediaEmbed', '-', 'Link', 'Unlink'],['Source', 'ShowBlocks'],['JustifyLeft','JustifyCenter','JustifyRight','JustifyBlock']]

  # ..snip..
  end
  Rich.insert
end