how do i fill in a pdf form

A similar online PDF editor called Fill is great if you just need to add a signature to the PDF

Add To Existing Layer Adds the content from the source document to an existing layer in the target documentSelect a layer from your target document

The imported content will have the same layer properties as the existing layer in the target documentThis option is available only when the target document contains layersCopy Layers From Source Imports the layers from the source document

This option is available only when the source document contains layersAdjust the Position and Appearance settings as needed, and then select OK

Merge or flatten layers (Acrobat Pro) Merged layers acquire the properties of the layer into which they are merged (the target layer)

Flattening PDF layers hides any content that is not visible when the flattening operation is executed and consolidates all layersThe development of these standards were aimed to address the many diverse needs of the printing and publishing industries

PDF/X-1a - Also known as the first standard of PDF/X family, PDF/X-1a requires all contents to be part of the PDF document in order to be able to be printedDocument elements such as fonts, forms, password protection, and visible annotations are not allowed

PDF/X-1a has its own specific requirements as well such as those pertaining to transparency and layers are permittedThese also require print elements to use only CMYK, greyscale or spot colours, resulting in no use of RGB or device-independent colour spaces