I riveted the top rib to the spar and skins. This completes most of the rudder assembly.
There are two major steps that remain however. The first is to rivet the skins and trailing edge together.
The second is to form the front edge of each of the skins so that they can be riveted together. This involves rolling the leading edges so that they are rounded inward toward each other and then riveted.
The process to do this is described in Section 5.9, which I need to review a few more times before attempting this step. I wouldn't want to mess up the rudder skins after all the time put into it prepping and assembling the rudder.