I was unsure of choosing "is"/"are" (is this not the third person singular present tense correct usage?), but besides that I felt like it was a coherent enough expression.

The "yourself" might feel awkward but is required to ensure that I am talking about the specific poster instead of something like "if you are not a X" in which case it would read like a general you.

If you understood what I was expressing and have a better and more succinct way to express it let me know.