rechtsverbindlichen Zeichnung

01:07 Mar 21, 2018 

but it's only a niggling doubt and I think you'll be fine with your version as it stands...

01:05 Mar 21, 2018 

my only doubt is that it might refer to the type of signature involved:

Der Verwaltungsrat bezeichnet diejenigen seiner Mitglieder, die für die Gesellschaft die rechtsverbindliche Unterschrift führen und bestimmt die Art der Zeichnung. buchermunicipal.com
The Board of Directors designates those Members who will have the legally binding authority to sign on behalf of the Corporation, and determines the kind of signature.

17:12 Mar 20, 2018 

... that this (non-)hyphenation issue is one of the frequently asked questions on English usage :-)

16:36 Mar 20, 2018 

... that there is no hyphen in "legally binding", even when used attributively. Adjectival compounds beginning with adverbs ending in -ly never take a hyphen (a successfully completed task; a frequently made mistake; a recently published book)

15:05 Mar 20, 2018 

I'm guessing this is part of a sentence, rather than a signature space at the bottom of a document, because you've put "rechtsverbindlicheN". Could we have the context, please?

"Authorised signature" is the more usual term if this is an individual signing on behalf of a corporation. And if you do use "legally binding", it has no hyphen because "legally" is an adverb.

We've actually had this before, but I suppose the context could be different:
http://www.proz.com/kudoz/german_to_english/law_contracts/74...