To add a Testsheet to the Ruletest in its editor, select the menu command Ruletest > Testsheet > Add Testsheet.

The Select Test Subject dialog box opens, as illustrated:

For the test subject, click on a listed Rulesheet or Ruleflow, as described in Choose a test subject in the Studio workspace

Click OK.

Corticon.js Studio creates a tab at the end of the current set of tabs, assigns the new tab a default name, and then opens the new Testsheet.