Gladiator's "Outmatch and Outlast"

Simple version.

Split arrow bow build.

In the descriptio it says "25% chance to gain a Frenzy charge on kill with Main hand".
Guessing bow = main hand. Been killing for hours now, not a single frenzy charge generated.

Am I missing something. Maybe my main skill (Split arrow) must be socketed in the bow instead of chest. Doubt it but maybe. If not then "Main hand" part does not count for a bow build. Anyhow, help needed, thanks in advance.

It seems, that you are playing bleed bow. Keep in mind, that you only get the charges, if the hit portion of your main hand weapon kills the target. You don't get a charge, if the damage over time from bleeding or the bleed explosion kills enemies.
This is exasperated if you use deadly ailment support in your link, because the hit portion of your attack is tiny.
This can be mitigated by utilizing culling strike to a degree.

If you want to use the "10% more Physical Damage while at maximum Frenzy Charges" portion of "Outmatch and Outlast" a combination of
+1 minimum frenzy charge crafts on rings an amulet
Pacifism Jewels (-1 Maximum frenzy charge)
and the "Disciple of Slaughter" notable can get you to maximum frenzy charges permanently.