Looking on the internet deeply has found these results:

skill in is the most popular phrase on the web.

skill on 1633,000 results on the web	skill in 130,900,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	Beurling demonstrated considerable skill in training. I ask because you seem to have developed some extraordinary skill in getting silent people to open their mouths. Your skill in combat must equal that of the legend himself. Peverara was singularly lauded for her skill in this genre. Another exercise in Section II develops a skill in recognizing, creating, and changing judgments. But I have some skill in saving lives. Your skill in combat must equal that of the legend himself. All successful people have this skill in abundance.

skill on

1633,000 results on the web

skill in

130,900,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

Beurling demonstrated considerable skill in training.
I ask because you seem to have developed some extraordinary skill in getting silent people to open their mouths.
Your skill in combat must equal that of the legend himself.
Peverara was singularly lauded for her skill in this genre.
Another exercise in Section II develops a skill in recognizing, creating, and changing judgments.
But I have some skill in saving lives.
Your skill in combat must equal that of the legend himself.
All successful people have this skill in abundance.