It's doubtful any of the platforms that RankerX posts to will allow iframe embeds. Pretty much any platform that allows UCG will be stripping iframe and embed tags by default, unless their devs are completely clueless about security.
Do you understand English, Amigo? I said "insert into the article". Open the article in your rankerx (if you have it) and paste the code into. That's all.RankerX is primarily used for creating and managing multi-tier link building campaigns and does not support the direct addition of HTML code or the embedding of iframes