“I just posted the letter below. I wish that there would be more options for us to chose when we comment on other letters.” 

What “letter below” does your comment refer to?   Why wouldn't you attach your comment to that letter?

The only “comment below”  I could find from you - referred to a guy who had been fired from his job for an inappropriate joke.  Totally irrelevant to the article.  

Maybe “relevance and coherence” should be more options to choose.