Trying to have Rails Admin timezone match with form timezone select

User.rb

validates_inclusion_of :time_zone, in: ActiveSupport::TimeZone.us_zones.map { |z| z.name }, 
message: "is not a valid time zone", 
allow_blank: true

 # This allows me to display the time_zone as a dropdown in rails admin instead of a text box
 TIMEZONES = ActiveSupport::TimeZone.us_zones.map { |z| z.name }
 def time_zone_enum
   TIMEZONES.each_with_index.to_a
 end

userProfile.html.erb

<%= f.collection_select :time_zone, ActiveSupport::TimeZone.us_zones.map { |z| z.name }, value, name %>

# I don't know how to get the value to be an index of the map operation and to display the name