If it is regular visitor to your garden it must be getting some food either in your garden or in a neighbours garden - for example seeds dropping off a bird table. If you can work out what it is living on, you might have more luck trying to bait it with the same food. In my limited experience, if they are used to eating bird table droppings or hen/chicken food, they are not necessarily going to be interested in something new like peanut butter or nutella.
In any case they are more likely to be interested in your bait/attractant if their normal source of food has been removed or "hidden"
They seem to like to eat near some sort of cover, rather than out in the open.
A few times we have just had solitary visitors to the garden rather than a family, and they do seem to be creatures of habit in terms of the time of day when they feed - so if you have seen the rat at one time of day, that might be a good time of day to look out for it with your gun.
Don't use 'solid' bait as it will just pick it up and leg it. Peanut butter works for me as they have to stop in their tracks to eat it or a little pile of small grain bird seed if that's what they/it are used to. Is it usually out in the daytime ? Note what time if you can, they are creatures of habit. Now, if it is a daytime rat, there are most likely more around as the dominant ones push the smaller/weaker ones out in the day to leave safer/richer pickings after dark for themselves.
Having said all that, I've caught many in a standard rat trap at home once I've Sussed there runs which is usually alongside a wall or fence.
Good luck Mel and let us know how you get on
HW77K .22, HW100KT .22, HW95K .22. AA TX200 MK3 .22. AA S410 MK3 .177. HW80 .25 HW30S .22. Pistols: Walther CP88 .177, Hatsan Mod25 Supercharger .22, HW45 Silver Star .177, Webley Alecto .177, SMK Victory CP2 .22
.22 airsporter time
Start leaving an outside light on.. They will get used to it. Cheaper than NV
Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.