Just wanted to let folks know about https://dmarcian.com/ . They have a bunch of tools that assist in setting up your SPF, DKIM, and DMARC resords, as well as monitoring their impact and effectiveness. Full-featured accounts are available for a two-week test period - useful if you're just setting up your domain - and if you're only monitoring one or two domains, they offer a feature-reduced (though still extremely useful) ongoing account tier for FREE.
I highly recommend giving them a try. I was able to identify non-compliant emails originating from our hosted Wordpress site, and take action to bring them into line before locking down my DKIM policy.