Multiple textures for 1 asset

Newbie here! I have a sign that i would like to update to include different textures so that people can choose a texture that suits their route. I tried the string table but after no errors I cannot change the asset's texture in surveyor. Can anyone help me?

Here is the config:
kuid <kuid:883564:100564>
kind "scenery"
username "QRail External Station Sign 10+"
author "Death2018"
trainz-build 4.5
description "Renamable 2010 modern livery Queensland Rail/Translink sign"
category-class "BR"

mesh-table
{
default
{
mesh "sign2010.trainzmesh"
auto-create 1

effects
{
0
{
kind "name"
fontsize 0.059
fontcolor 255,255,255
att "a.name0"
name "name"
}

1
{
kind "name"
fontsize 0.059
fontcolor 255,255,255
att "a.name1"
name "name"
}
}
}
}

string-table
{
texture_name "Livery"
texture_description "What livery should we have?"
description_skin "Skin"
skin_0 "V1"
skin_1 "V2"
skin_2 "V3"
skin_3 "V4"
skin_4 "V5"
skin_5 "V6"
skin_6 "V7"
skin_7 "V8"
skin_8 "V9"
skin_9 "V10"
skin_10 "V11"
skin_11 "V12"
select_skin "Choose a Skin"
}

thumbnails
{
default
{
image "thumbnail.jpg"
width 240
height 180
}
}

kuid-table
{
qrailtextures <kuid:883564:100838>
}

making seperate assets with different textures is easier on the frame rates. (Reskin)

Cheerio John