Were the contracts user generated, or your own standard template? If the latter, then embedding your own signature tags into a standard template seems like the

Were the contracts user generated, or your own standard template? If the latter, then embedding your own signature tags into a standard template seems like the simplest use of DS API. Wondering why their tech support didn't share this solution. Or maybe it's no longer supported(?) (Full disclosure: I helped design the DS REST API and their Salesforce AppExchange app many years ago)