Fuel Treatment Advice Please

[installer]

Got my self a bottle of -

Fortron Diesel System Treatment 325ml

From my local dealer this morning while had my steering controls replaced.
But it says on the side " One bottle is sufficient to treat 80 litres of fuel".
So do I shove the lot in on to 3/4 tank of fuel (v-power diesel if it makes any difference).
Or do I put 1/2 in now and on the next tank put the rest in?

How should it be done?or recommended to be done?

[VauxVeteran]

I used to treat half a tank per bottle, putting the whole lot in now at three quarters full wont harm it.

[parapaul]

I think the wording gives it away...1 bottle is 'sufficient' for 80 litres of fuel. Unless there's any direct warnings about dosing, I'd stick the whole lot in

[installer]

Right I`ll go and shove it in then.
Trip says used 3.8g so that`ll be approx 40l left in