Unfortunately you cannot do this, in order to be sent to PS the file has to be rendered as a psd, tif or jpeg file.
This is the only way to way to do it. The secret is to do as much as you can in LR first including the calibration which should be done before PS and not after. I cannot see how it would help any other way?
Adding to Alfred's good advice - a raw file can not be saved like other files.
Its only use is as being the basis for creating new files, which have to be regular files, like tiff, psd or jpg.
When you edit a raw file in Lightroom, it doesn't change the file, the edits are written to the catalog.
You can, optionally, save the edits as metadata to sidecar (xmp) files, or in the case of DNG to the file itself.
Thank you! This helps.
You can do this using a Smart Object, but all editing of the raw file is then handled by Adobe Camera Raw. The Smart Object file can also be edited in LR. The one down-side is that Smart Object files are very large.