<apex:page sidebar="false" standardStylesheets="false" standardController="Custom_Object_A__c">
<apex:form>
<apex:pageBlock title="Create Two New Records">
<apex:pageBlockSection>
<apex:inputField value="{! Custom_Object_A__c.Name}"/>
</apex:pageBlockSection>
<apex:pageBlockSection>
<apex:inputField value="{! Custom_Object_A__c.Custom_Object_B__r.Name}"/>
</apex:pageBlockSection>
<apex:pageBlockButtons>
<apex:commandButton action="{! save }" value="Save" />