How can use existing Bootstrap framework into our development

I get bootstrap responsive skin option when creating a new skin, But I found that we can upload bootstrap framework into other assets and use the normal bootstrap classes to our html elements inside of components. My question is what is the purpose of Responsive peak skin? When should we go with it?

We are unable to use existing bootstrap framework, which is imported from " Responsive Peak Skin"  and we are imported new package through "Assets Library "->  "other Assets".

Please guide us the such a way to avoid adding bootstrap package.