Where to connect rear fog light wire from bypass relay

Apologies if this has been covered by I can't find an answer. I'm new to both Octavias and rear fog lights. I have a 2011 Octavia estate and am installing a Quasar WH2Q-S-G7 bypass relay for a trailer. Everything is connected and working except the rear fog light connection. I can see that there is only one wire for the running/rear fog light and the light somehow brightens when the fog light switch is activated. How should the rear fog light wire from the bypass relay be connected? Any help would be appreciated. Thanks.