In Spain
Samantha or
Samanta (the adapted to Spanish/Catalan/Basque/Galician/Occitan spelling) is not used.
There may be any Samantha/Samanta, but just as there may be any
Montserrat... in USA.
(In Catalonia, there are 311 girls named
Samanta [#627 in total of names] and 249 named
Samantha [#745].)
Lumia
http://onomastica.mailcatala.com