How can I use a relative path in my toml file?

I want to use a relative directory in toml file. I heard that I should use "\" instead of "" in toml file, but I don't know how to use relative path in toml file.

HatMode = "Custom"
HorizontalSize = 1.5
HatPosition = 0.600000023841858
CustomHatPath = "C:\\Users\\Desktop\\kane_goose\\DesktopGoose_v0.3_Extractor\\Assets\\Mods\\HatGoos\\kane.png"

This is codes inside of toml file. I should enter a relative path in CustomHatPath = "C:\\Users\\Desktop\\kane_goose\\DesktopGoose_v0.3_Extractor\\Assets\\Mods\\HatGoos\\kane.png" this part.

Below, directory of the first image is C:\Users\username\Desktop\kane_goose\DesktopGoose_v0.3_Extractor\Assets\Mods\HatGoos , and directory of the second image is C:\Users\username\Desktop\kane_goose\DesktopGoose_v0.3_Extractor\Assets\Mods\HatGoos\hat

The toml file is on the first image, and I must add the kane.png of the second image to the toml file.

Can you teach me how to use relative path in this situation? in toml file?