Full Idea
Kripke explicitly allows for the introduction of names through initial reference-fixing via descriptions. Versions of the causal theory of reference that disallow this would have a difficult time explaining how the name 'Neptune' came to refer.
Clarification
Neptune was predicted before it was discovered
Gist of Idea
Some references, such as 'Neptune', have to be fixed by description rather than baptism
Source
report of Saul A. Kripke (Naming and Necessity lectures [1970]) by Zoltán Gendler Szabó - Nominalism 4.2 n35
Book Reference
'The Oxford Handbook of Metaphysics', ed/tr. Loux,M /Zimmerman,D [OUP 2005], p.30
A Reaction
The initial reference to Neptune has to be by description, but you could still give a baptismal account once it is discovered. The direct contact now takes precedence. Suppose another similar planet was found nearby...