I have added multi-language using the short article below.
When you add for example German language you will have these files: formMain.resx formMain.de-DE.resx for
I found the answer
Click the Setup Project in Solution Explorer and then click Add\Project Output\ . From dialog select the project for which you want to include localization (satelite) assemblies and then select Localized resources.
After the installation in the folder that I install to, I have the th-TH folder which includes the satellite assembly.
Thanks,