Question: Given a random sample $X_1 ... X_n$ from a cdf $F$, derive the asymptotic distribution of the the sample mean, $\overline{X}$.
I am not sure what is being requested here. Does one just need to apply the Central Limit Theorem?
In that case
$$ \sqrt{n}\frac{\overline{X}-\mu}{\sigma}\to_{(d)}\to Z \sim \mathcal{N}(0,1) $$
In that case I rewrite
$$ \sqrt{n}\frac{\overline{X}-\mu}{\sigma} = \frac{\sqrt{n}}{\sigma}\overline{X} + \left(-\frac{\mu\sqrt{n}}{\sigma}\right) $$
So I end up with
$$ \overline{X} \sim \mathcal{N}\left(-\frac{\mu\sqrt{n}}{\sigma} , \frac{n}{\sigma}\right) $$
Does this make sense?
No, the answer should be $\mathcal N(\mu, \sigma^2/n)$. Of course this is assuming the distribution has a finite variance.