Drop of ink in reish

Found this tiny dot of ink inside the reish of asher. what are your thoughts? Is this enough to pasul the reish? Enough that it’s a sheila l’tinok? Or not an issue at all?

If the image doesn’t do justice - it’s really a tiny dot of ink.

I note that the yalkut hasofer of sefer mishnas hasofer writes under os daled: if a small drop of ink less than an os ketana fell inside the daled, then if a tinok reads it as a daled there is room to be lenient and scrape it away...

I wonder how small is small...