I'll do up a proper demo at some point but at it's simplest you'd just want to call the tinymce (v4) function on the field in question. If it's a basic input field, convert it to a text-area first. There's a couple of cleanup things I want to do on both scripts so I'll look at adding the rte option into the next version.
Is it possible to add a second RTE to a Page to add in unique content using this extension?
No, not yet. I'd more than likely be adding a RTE metafield popup (or similar) into the ShopifyFD first so once that's working nicely I'll port some of that across here. There are easy ways to split content from within the one RTE so you may not even need this extension - make sure you're not over complicating things for yourself or client.
Will you be willing to post the non-minified js file for the Custom Fields on github?
Yes, but not immediately. Once the main functions I'll blast that up for everyone to pick apart / mod / fix. The main logic is pulled from ShopifyFD so if you're looking for some inspiration - check out the source for that.
I'm having trouble fully converting the basic input fields in Custom Fields to textarea's. I am able to convert the input so that it is now a text area, but the "Save With Custom Fields" button in the upper right corner does not appear. I am not sure how to update the saving functions and my trial/errors have failed so far.
Do you have any tips?
William - I had hoped to have those text areas added in but work got the better of me these last couple of weeks. It is something I plan to add in. Now that I've got a couple of design and dev helpers on board I can spare a bit more time for these things.
If you're not seeing that save button the script must failing somewhere, in the functions that setup the UI on the page. What errors are you getting in the console?
Part of the issue with making the inputs into a textarea is that the code is only looking for inputs. Eg, on the product page the save function nabs the fields with:
var inputs = $('div.custom_fields_box input');
You'll need to account for that, though I might just amend the code for that part tonight. It won't break anything by including text areas in that group.
 Basic textarea support added. I'll upload it shortly.
I'm new to Shopify so forgive me if this is too basic of a question... but how is this different than the Metafields2 app? It seems it's within the Shopify interface whereas that app seems to take you to another website, but is the function the same? Being to provide a non-dev interface for creating and editing metafields?
...Being to provide a non-dev interface for creating and editing metafields?
This one is yes. So a way for designers and devs to give the client some metafield control without making them freak out with too many options. For more advanced editing, use the parent tool - shopifyFD.
Hi Jason. Thanks for your work on this - looks like a super handy tool, though unfortunately I'm not having much luck so far... I've attempted to add new metafields with the ShopifyFD tool, which appears to be successful (I have a "1" beside "Metafields" in that box), however I can't get any to show up in the "Custom Fields" area created by this tool. All I get is "No custom fields found".
I've tried adding new metafields in the product window, and using the bulk metafields tool, but neither are showing. I've entered namespace, key and value with no spaces, all lowercase.