In languages files, RubyMine creates stubs of documentation comments on typing the opening tag and pressing EnterEnter.
Documentation comments can be created in accordance with RDoc and YARD syntax. Note that RDoc highlighting in documentation comments can be turned enabled or disabled in the Appearance page of the editor settings.
When you create additional tags, RubyMine provides code completion that suggests the possible tag names.
Documentation comments in your source code are available for the Quick Documentation Lookup and open for review on pressing Ctrl+QCtrl+Q.