As Lisa says, it is acceptable to simply print the preparer's name on the return as the signature.  That's usually the default in software, AFAIK.

In case you are curious, the authority is from §6061 and the rules are prescribed by the IRS in Notice 2004-54.

FWIW, for returns that can't be e-filed for whatever reason, we do upload the packaged filing copy to our secure client portal with clear instructions for the client to print, sign, and paper file.  Whether that's suitable would depend on your client base, for example, whether they are tech savvy or not.