Filter → Roughen segments an outline into straight line segments and randomly moves all resulting nodes within a given limit. Control the size of the line segments with the Segment Length field. The Horizontal and Vertical values control the maximum offset for each node. The custom parameter rule is as follows:

Roughenizer; Length; Horizontal; Vertical

For example, the following rule would match the Roughen dialog window shown above:

Roughenizer; 15; 15; 10