No, it only supports one file in the native script step. This has been heavily discussed, please search the forum for previous posts about it.
Your options are:
1) use a mail plugin that supports multiple attachments
2) Append the PDF into one PDF file so it can be sent as one file
3) Send separate emails, one for each file
4) Write an applescript or system script that will zip multiple files so you can send a zip file.