Your parameter is incorrect and to answer your question of URLFOR Explained:
<apex:outputLink value="{!URLFOR($Action.Admin_Tracking__c.New, null, [RecordType='012230000004LDD', save=1])}" target="_blank">Advanced Entry</apex:outputLink>
http://salesforcesource.blogspot.com/2008/12/urlfor-function-finally-explained.html
{!URLFOR(target, id, [inputs], [no override])}
Parameters shown in brackets ([]) are optional.
target: You can replace target with a URL or action, s-control or static resource.
id: This is id of the object or resource name (string type) in support of the provided target.
inputs: Any additional URL parameters you need to pass you can use this parameter.
you will to put the URL parameters in brackets and separate them with commas
ex: [param1="value1", param2="value2"]
no override: A Boolean value which defaults to false, it applies to targets for standard Salesforce pages. Replace "no override" with "true" when you want to display a standard Salesforce page regardless of whether you have defined an override for it elsewhere.
Although, this will not do what I suspect you actually want and bypass the record type selection page. Currently no way to do that using URLFOR
Alternate way of doing this: Build the url
http://blog.jeffdouglas.com/2010/03/30/short-cut-the-recordtype-selection-step/
/006/e?retURL=%2F{!Account.Id}&accid={!Account.Id}
&RecordType=YOUR-RECORDTYPE&cancelURL=%2F{!Account.Id}
Related Idea: https://success.salesforce.com/ideaView?id=08730000000BrRqAAK
Alternate solution: if you only have one record type assigned to each profile then the selection screen will not be presented