宛てる is read as あてる (ateru) and means to address.
あてる
ateru
あてさき
address
あてな
name and address (on an envelope, etc.)
あてがき
addressee's name and address
あてながき
addressing (e.g. writing an address on an envelope)
あてさきあどれす
destination address
あてしょ
address (of a letter, parcel, etc.)
えんてん
(of eyebrows) shapely
えんぜん
as if
あてさきへんこう
redirection
あてじ
kanji used for their meaning, irrespective of reading
てがみをあてる
to address (direct) a letter to a person
あてがいぶち
discretionary allowance