Did you ever find out?  Were you looking to have a different signature based on amount? Thanks!

common information / Maintenance / CI setup / set up business forms/ [select check type] / Design / right click on signature field / edit formula

trying to tie auto signature to class of vendor.  appears only able to tie to field in check.  now transitioning to Oracle, so did not pursue deeper solutions

Thanks I see the area but still trying to figure out how to make the signature change based on the check amount. 

When you are on the signature image within Crystal Reports, right click and go into the format editor.  Under the common tab, you can create a formula to suppress that image based upon the total check amount.  You basically need multiple images each with their own suppression formula.  Hope this works.

Eeekk! Yes this was a huge help. Thank you in pointing me in the right direction.