I have 1/5N NaHO solution. The test with the pH meter call for 1/10
(0.10) solution.

Can I use the 1/5? I assume I can. Would I double the result?

Normally TA test kits use .2 N NaOH. Becasue then if you use a 15 mL
sample of wine the volume of NaOH that you use is equal to the .1% TA.

So if you use 6 ml of 0.2 N NaOH then you have a 0.60% TA wine.

If you use the 0.1 N NaOH in that "standard" protocol you will have to
HALF the ml of NaOH you used to titrate the acidity (or half the wine
you use).

But since your protocol is set up for 0.1 N, yes you then double the
result.