Thank you for your interest in BSS extension. The M2 Request for Quote doesn't support out of stock products so if you want to set Add to Quote with out of stock items I regret that our module doesn't have this function. ​If you want to enable Add to Quote button in specific products, it will work when you install the M2 Hide Price extension as well. The M2 Hide Price & M2 Request for Quote extensions work well together. If you have any other questions, please feel free to let us know.