Perch Form Template Tag perch:input type file
This will create a file upload field that accepts file formats. The allowed formats are defined in the file
type="file" you should also use the attribute
accept with a string of mime type groups from
filetypes.ini that are acceptable to be uploaded.
<perch:input type="file" id="cv" accept="pdf doc">
Remember if using file inputs with the Forms app, you need to configure a file upload location within the form options.