We have a double SPF record (it's double now, it was a single entry before). One line is for a commercial service and the other is for an IP that sends to us as well. The entry is set as TXT and is laid out like this:
I have obscured the IP but otherwise that is what is there. We started having rejections of email sent to email aliases for our domain two days ago, so we added the second line about 24 hours ago.
We do registration through Godaddy and use Route 53 for management.