Define custom registry npm

Question

I defined my custom-registry

@custom-registry:registry=someURL
registry=someOtherUrl

And then i want to use it inside package.json

"devDependencies": {
"@custom-registry/desiredPackage": "*"
}

but during downloading i get error

error An unexpected error occurred: `"https://someUrl/@custom-registry%2fdesiredPackage: NotFound".`

I see there is problem that after someUrl is @custom-registry but how can i specify which registry should be used and not have that reigstry in url. (correc url should be - https://someUrl/desiredPackage)