The standard form of the Shakespearean or English sonnet consists of fourteen lines of iambic pentameter. The rhyme scheme is three open quatrains followed by a couplet, or a-b-a-b, c-d-c-d, e-f-e-f, g-g, where the letters stand for rhyme sounds. The English sonnet normally has some sort of structural shift or turn between the quatrains and the final couplet. Sometimes the English sonnet has a hybrid thematic structure, using a Petrarchean or Italian turn, normally found after the octave in the Italian form, after the second quatrain and a seond turn before the couplet.
Because the Prologue only consists of 10 lines, it is not a traditional sonnet. On the other hand, its structure of two quatrains and a couplet resembles a sonnet with a missing quatrain. The defective form imitatively is intended to suggest the lack of skill of the player as this section of the play is intended as comic.
If we offend, it is with our good will.
That you should think, we come not to offend,
But with good will. To show our simple skill,
That is the true beginning of our end.
Consider then we come but in despite.
We do not come as minding to contest you,
Our true intent is. All for your delight
We are not here. That you should here repent you,
The actors are at hand and by their show
You shall know all that you are like to know.