Since RD is based in EU - they’re advertised cost is in euros. When you sub to a premium pkg, your payment will covert currancy to USD costs. The site also lists what the USD conversion rate cost is under their advertised euro cost under each pkg.
Nothing sketchy.
Once you review Troy’s guide that he provided, you’ll see that it’s relatively easy to set up for each app that you intend to use it for.
In the end, however, if you’re still feeling apprehensive about purchasing a sub, then you shouldn’t.