Quick Tip – The PowerShell code below adds it as a Site Column, once you do that  navigate to your custom Content Type and add it from existing site columns.

Add-PSSnapin Microsoft.SharePoint.Powershell -ErrorAction SilentlyContinue

$fieldXml = <Field Type=Geolocation DisplayName=My Location />

$web = Get-SPWeb $webUrl
$fieldName = $web.Fields.AddFieldAsXml($fieldXml)
$web.Update()

 

Cheers,

Oscar