If you need clickable links in a custom form, you can use VBScript code and a Label field or Command buttons to make clickable links.
Outlook 2013 Custom form: Tiny text bug (Fixed)
[Fixed] Outlook 2013 RICHED20.DLL bug: the font used in the first field on a custom form is tiny. The field properties look fine, the font size is set to a reasonable size, like 8 point, but the text is very small.
Publish a custom form in another user's mailbox
Publish a template to another user's mailbox using a macro or a custom form.
Migrating custom forms to a new Outlook version
When custom forms aren't working as expected, check to see if scripts are enabled in folders. I'll show you when to check.
How to clean up Outlook's Forms Cache
When Microsoft Outlook forms are giving your problems, you may need to clear Outlook's Forms Cache.