In reference to the following page of Saga, Issue #1, page 5 (written by Brian K. Vaughan, art by Fiona Staples) I will be discussing the use Kannenberg's theory on lettering, metanarrative, and font.
The lettering used in this particular page varies between captions and within speech bubbles. The captions are what affect Kannenberg's idea of the metanarrative the most. In comparison to the bolder text used within the speech bubbles, the captions look much more hand-written and soft around the edges. Furthermore, in comparison to the other fonts especially, it is actually quite small. This affects the way the reader would read it; almost giving it a "smaller" or "quieter' voice. In relation to what we know/eventually learn from this issue, this "smaller" voice makes sense, since it is representing the baby of the characters shown here (Marko and Lana). Thus, the connection left from the metanarrative makes sense.
The other use of lettering, less in relation to metanarrative and more in relation to the narrative itself/the font, is the speech bubble in the second panel with the larger and bolder font. This represents the loudness that the scream would represent; we know it's a scream because of the exclamation mark as well as the "ahhhn" sound effect with it, and the fact that the font is not only bolder but larger adds to this effect.
To that end, in relation to theories on lettering and such, this page of Saga gives a few examples of how it can effect metanarrative and the narrative in general.