How do I map an SFDC custom field with a field on a Marketo form?

If you've created the field in SFDC, Marketo should automatically recognize it.  However, if you created your form in Marketo with a different field, before creating the comments field in SFDC, you will probably need to update your form with the correct field.  

Not exactly sure what you are asking or what your obstacle is, though, as there isn't much detail in your question..

SFDC "Description" already matches to marketo's Person Notes.

As Nate said, you may not have created the field correctly and we're not sure what the question is. I'd suggest asking Support to help you connect the fields if they weren't mapped already.

Is it possible to link a field in a Marketo form with the comments section of task detail in activity history in salesforce??

To Elaborate:
When someone fills out a form on Marketo, it shows up as a task in salesforce. There is a certain field on my Marketo form that I want shown up in the comments section of the task detail. Is this possible?

- Isabela

you should be able to do this by modifying the field tokens in the Comments section of your Create Task flow step.  Instead of using the default {{Lead.Email Address}} etc. etc. you could try dropping in {{lead.Person Notes}} as Josh mentions above, or whatever the field is where your lead's notes reside

Where do I find the flow step in Marketo that creates a task in salesforce?

Hi Isabela,

Simply go to the flow step of any smart campaign and in the right hand search bar type "Create Task".  This will filter out all other options and leave you with the create task action as per screen shot above. 

Nate

Hi Nate, thanks I was able to find it. I don't have this flow step set up, yet it still creates a task in the activity history section of salesforce. If I implement this flow step, will it replace or update the existing task in salesforce?

Thanks