Missouri follows Federal e-filing process and discontinued the use of its own authorization form with TY2017.  See the FAQ on how to sign.

https://dor.mo.gov/faq/personal/efile.php

Here's an article from Intuit.  But given Intuit's track record on updating articles lately, I'd always take a look at other sources (hint: check knowledge base of other tax software).

https://proconnect.intuit.com/community/help-articles/help/which-states-require-a-signature-form-whe...